Archive of Our Own ^beta

Chapter Text

Denki knows full well that there’s never really been a question needed as to whether the mer exist. They ‘exist’ to humanity these days in the same way the true fae and titans do: in fossils and relics, and stories from an age when magic held the world carefully in its palms and instilled new wonders with every gentle whisper.  

It’s not like magic is gone— far from it. But the creatures that breathed magic, bled it, held together by miracles and timelessness and enigma… well, they’re another story. It’s a basic fact established by his current employers, afterall. As a marine technician aboard the expedition ship RV Shinkai Maru with the strangest collection of magizoology researchers and interns he could have imagined, he’s more in tune with the history of the mer than your average joe.

 So, yes. He knows merfolk existed , once upon a time. But after centuries of silence from beneath the waves, he—like everyone else—had accepted their disappearance alongside so many other mythical species. 

Which is why he’s having a hard time comprehending the visual feed from his sea rover.

“Erm— Uraraka?” he calls out a bit shakily, unwilling to pull his gaze from the screen in case the drifting purple-grey shape disappears. He’s having to nudge the rover every few seconds to keep the thing in the headlights; as of yet it hasn’t made any sharp moves at all, but it would be just his luck for something to happen the second he takes his eyes off it.

But there’s no response from the marine veterinarian intern; she must still be in the break room. Instead, he reaches blindly along the table towards his left, tapping and waving to get the attention of his fellow engineer, a surly blonde wearing headphones with the music so loud Denki can almost make out the words. Bakugou’s never been friendly by any means, but Denki’s desperate. He needs someone else’s eyes, anyone’s — just to offload some of his shock, if nothing else.

His hand is swatted away, followed by a grouchy “What,” that’s a bit louder than absolutely necessary. But at least he has the jerk’s attention.

“I need you to see this,” Denki says, adding a quick gesture to the screen. “I can’t— I can’t tell what I’m looking at.”

“Wouldn’t be the first time.”

“Bakugou, please. Come look. I think it’s… it’s a…” he swallows, unable to push the word past his teeth. If he says it and he’s wrong, Bakugou will be shouting the mistake through the mess hall at dinner, and Denki won’t live it down for the rest of the expedition. 

Thankfully, Bakugou saves him the potential embarrassment by grumbling and swinging his chair closer.

They peer at the shape together. The grainy rover camera isn’t the best at picking up details, and down where it’s been chugging along everything’s got a distorting blue hue in one way or another, but still— this stands out.

What had drawn Denki’s attention was a long, aubergine-colored tail and violet fin plumage that’s drifting broadly around the end and sides like sheets of silk. The rover’s glow catches a shine on some harder scales that glint like embedded amethysts in the light. But now, Denki holds his breath and maneuvers the rover once again to the view that had his heart hammering in his chest and hopes caught in his throat; the beams slide upward from the tail across a very humanoid torso.

He hears Bakugou’s low intake of breath, and for a moment the only noise apart from the far-off engines is the music still playing, weak and tinny, from the headphones around the other man’s neck. Then: “Move— move the fuck over, Creaky, let me...”

Denki ignores the nickname for once, pulling away from the controls. 

Bakugou slides into place, eyebrows knitted and hands expertly working the controls. The rover strafes to the side, pivoting around the unmoving creature. As it shifts, the beam tracks down an honest-to-gods arm that ends in five taloned digits, lax and half-curled where it rests just inches from the camera. 

Beside him, Bakugou lets out a quiet ‘what the fuck’ and that’s enough for Denki to let a thrilled grin tear across his face, because holy shit, this is real.

And then the view feed rolls on, and there’s a shoulder, then a gilled neck, and finally face with a fin-like ear on either side and closed eyes and—

“How far down’s this rover?” Bakugou asks sharply. His voice is surprisingly neutral for what’s happening, but the tension in his back and slightly wider-than-normal eyes give him away.

“Only like, two-forty.”

“Does it have its net equipped?”

“Ye—” Denki cuts himself off, finally tearing his gaze away from the merman (again, holy shit ) to stare at his coworker. “Y-yeah... it does. Are you going to…”

“I ain’t going to believe this isn’t some dumbass prank til I see it with my own eyes.” He puts his lower lip between his teeth as the rover comes back around, shuffling it backwards until the entire prone, drifting body of the creature fits within the net deployment guides on screen. “And if it ain’t a prank...” he starts slowly, then closes his mouth. In lieu of trying to find the right words to fit this unforeseeable circumstance, he turns his severe stare to Denki. “Go find the cockatoo guy and bring him to the starboard docking pool.”

Denki blinks. “Cockatoo guy?” 

“That one blonde researcher that’s obsessed with these fuckers. Squawks nonstop during mess. Used to have a radio show?”

Right. “Professor Yamada,” he mumbles, not that he thinks Bakugou will bother committing it to memory, if the fact that he refers to nobody by name is anything to go by. 

Bakugou grunts in acknowledgement, and then smacks the net deployment button. Denki watches with bated breath over his shoulder as ropes snap out from a space beneath the rover’s camera and snag around the creature, which… doesn’t react. That’s not promising.

Denki hauls his legs around with shaky hands, careful not to bash the mechanisms of his knee and calf braces against the edge of the desk. Really, Bakugou should be the one going to get the research team if they were gunning for speed, but he supposes this is his colleague’s way of giving Denki the credit of the find. He appreciates it— even if the dude’s an ass. 

He shoves himself to his feet, taking a moment to find his balance. On the screen, the merman has yet to move despite the slow reeling-in of the net.

“Go on, and don’t fucking fall over on the way,” Bakugou growls, shoving Denki’s cane roughly into his hands. “You better fucking have it aboard by the time I get up there if I’m putting in all the goddamn work. Go. ”

Denki goes.

“...I-I swear I’m not fucking with you— er— pardon my French, sir,” Denki trails on in as quiet of a voice he can, growing increasingly anxious at the stillness of Professor Yamada’s normally-exuberant face. His legs ache from pushing them so hard, and it’s taking all his admittedly limited self-control to not sit on the ledge of the docking pool. “Bakugou wouldn’t have asked me to get you if he didn’t believe it too, I think.”

It’s not only Yamada’s current state that makes him nervous. A few steps away is the professor’s husband, with tangled black hair to his shoulders and a near-permanent exhausted expression. The man has never bothered to introduce himself. Denki’s not sure the guy’s even a researcher, to be totally honest. Or even a fan of the ocean at all. He can’t recall ever seeing him anywhere other than below-decks, skulking in the shadows or tucked into an obnoxious yellow sleeping bag.

But they’re both here now, and frighteningly alert, not saying a word as the whirring machinery in the room languidly works to raise the rover and its captive. Denki shifts more weight onto his cane with a wince and a soft, sharp inhale.

The black-haired man glances over at him at that, and Denki ducks his head instinctively for interrupting his solemn contemplation. But instead of chastising him, the guy slinks over to the far wall to fetch one of the janky plastic folding chairs. 

On his return, he props it open next to Denki. “Sit,” His voice is unexpectedly smooth.

Denki nods gratefully and takes the seat. The aching falls away almost entirely and he sighs, not for the first time wishing it would stay that way. Seven years of healing and therapy could only do so much to remedy one brainless teenage error in judgment.

“You didn’t tell anyone else besides the other mechanic, did you, kid?” Yamada’s strange husband continues, making Denki jump. 

He glances up to see both sets of eyes trained on him. So much for the assumption that they’d return to uncomfortable silence; this could arguably be worse. 

“No! Of course not,” Denki murmurs back, earning a tense but genuine smile from Yamada and a grunt from his partner. The two look away from him and at each other so simultaneously that it raises the hair on his arms. “I didn’t want to alarm everyone, erm, just in case it somehow is a dumb prank left behind by someone else, which would be really shitty by the way, not that I think it’s a prank or I wouldn’t have asked for you, it looks very real, b-but I could be wrong ‘cause I’m not expert, a-and if so I’m really sorry for wasting your time—”

“Kaminari,” Yamada interrupts, and - wow, he didn’t think the professors even bothered to learn the names of the support staff. The man flashes another smile at him, this time with teeth. “Take a deep breath for me, will ya, listener? Even if it is a prank, you’re not in trouble! And I’m sure we’ll get a good chuckle out of it, won’t we, Shouta?”

‘Shouta’—Kaminari is almost positive that’s a given name and won’t dare use it—grunts again, gaze once again levelled on the machinery and open pool of water in front of them.

The bright yellow upper casing of the sea-rover breaches the surface.

Denki starts to rise from his chair, preparing to wrangle the device into position, but Yamada waves him back down and takes over the task. The rover itself is compact, roughly the size of a minifridge but capable of propelling itself unassisted through the water and sturdy enough to hold up at depths far deeper than it’s been used for thus far. It’s kind of Denki’s pride and joy of the expedition, so he has to bite back a grimace each time Yamada bumps it into the pool’s sides. 

Finally, it’s able to be hauled straight vertically, and Denki sees a first flash of vibrant color from the netting below.

He really does struggle out of the chair then, but ‘Shouta’ beats him to it, double-fisting the net and yanking it around for a clearer view of the shape inside. Denki can’t see past him, but he takes notice of the man going stock-still and the hissed ‘Fuck,’ that follows. 

Denki’s throat is dry. “What can I—”

“There’s a divided holding tank in the room next door. Get it filled from the external pumps.” The man swears again under his breath, struggling momentarily to unclasp a key from the ring on his belt before shoving it in Denki’s hands. “Don’t say a word about this to anyone you see. Do you understand?”

He can’t help himself; he stumbles sideways and catches a glance of greyish-lavender skin and purple neck gills that are fluttering, moving , oh shit it’s really alive — “Y-yes, mister… Yamada?”

“Aizawa,” the man corrects, hauling the netting further up until a breathtaking dark tail bumps the pool’s edge. “Any day now, kid, get a move on!”

The pain is a distant thought as Denki lurches from the room, leaving the pair to their agitated whispering. Footsteps thunder down the hall from the opposite direction and Denki nearly runs headfirst into Bakugou. He must be wearing quite the expression, because his colleague’s eyes inch wider in understanding.

“The—the tank, we need to fill the tank,” he stammers out, brandishing the key and motioning to the next door along. 

Bakugou nods wordlessly and grabs it out of his hand, easily beating Denki to the door and swinging it open. The room beyond at first looks like a storage room, with all manner of boxes and doodads piled about carelessly, but the truck-sized glass enclosure against the back wall is impossible to miss.

“Stay the fuck here, you’ll trip on something,” Bakugou growls, pushing the key back at Denki before maneuvering his way through the mess to the tank’s valves and control panel. One jarring pipe-squeak later, seawater slams into the interior glass wall, brown-green and frothing.

Not wishing to be entirely useless, Denki starts shoving aside the lighter objects littering the floor, clearing a path to the tank’s stairwell.

It feels like eons before there’s shuffling in the hall and Aizawa shoulders the door open and backs into the room, arms full. Denki scrambles out of the way and watches in mute awe as the man wrangles the upper half of a near-motionless form through the doorway, followed by Yamada who is barely keeping a grip on a long, thick tail. 

“Holy fuck,” Bakugou chokes out, and Denki nods in agreement.

Denki’s no expert on mer, but he’s pretty confident that this one’s male, if there’s anything to be said for likeness to humans. He resolves to look up some more specific shades of purple because from horns to tail there’s no better single adjective to describe the fella. Right now, however, the hair that looked so ethereal on the rover’s camera drips down over speckled cheeks and long ear-fins, blackish lips part soundlessly with gills bubbling out air, and blood drips from a series of gashes on his bare lavender chest.

The two men struggle to climb the tank steps with their burden, which is hardly surprising; the merman’s waist to tail alone must be six feet at least. Then, Yamada falters on the second-to-top step and accidentally pinches a pelvic fin against the metal railing—

And the merman explodes into movement, letting out an ear-piercing shriek. He writhes against his poor handlers, throwing what must be hundreds of pounds of scale and muscle back and forth. Denki can only watch and call out a warning as Bakugou scrambles up the steps to help, and the next moment a railing clatters noisily to the ground, and—

SPLASH.

He’s showered with droplets even from several feet away.

“Bakugou!” Yamada shouts.

The scene in the tank is chaotic, six limbs and a tail and too much splashing to make any sense of what’s going on. Bakugou’s strong, he knows, and thankfully there wasn’t yet enough water in the tank to reach past the other blonde’s shoulders when standing, but still — Denki’s pulse hammers in his throat and he hobbles for the intake valve just in case.

When he looks back, Aizawa is leaned half into the tank, one hand tangled in a cloudy mane of purple hair which he holds against the glass just under the surface. The merman’s lips are pulled back in a wordless snarl across bared shark-like teeth.

Bakugou is standing on the opposite side, shoulders hunched and covering one of them with a hand. “The asshole bit me!” he roars between coughs. “I saved you, you stupid fishy fuck! Bleed out for all I care!” He edges toward the tank wall attached to the stairs, but rethinks it when a rumble echoes through the water and the merman’s tail thrashes.

There’s a knock at the door. “Hello? Is everything alright in there? I was passing by and couldn’t help but overhear… is there an injured fish…?” Uraraka’s worried voice trails off.

Denki looks to Yamada for guidance, who looks at Aizawa, who drops his head in defeat. Bakugou at least has the sense to look guilty, murmuring something along the lines of ‘at least she’s a vet’.

“Uraraka, do you happen to have any medical experience with humanoids, too?” Yamada calls out.

“Um? I have b-basic first aid training, and then a bit more, but I can go get the doctor if someone is badly hurt—”

“No no, you’ll do!” Yamada squeezes the bridge of his nose. “We’re going to let you in, but you mustn’t speak a word of this to anyone else, alrighty, listener?”

“O… kay?”

Denki takes a deep breath, heads to the door, and pulls it open with a half-apologetic smile. Then he steps aside.

Stepping in, Uraraka flicks her gaze between the group of them before finally landing on the tank. “Oh," she says weakly, hands going limp at her side. "Oh my god.”

"If you don't mind," Yamada continues with a brilliant smile bordering on manic, "Would you quickly go fetch your medical supplies? The water's color is growing alarming, and we can't risk losing a mechanic."

As if on cue, Bakugou sways against the glass inside the tank.

"Oh my god, w-what?!"

Chapter Text

It takes three of them in the tank and Aizawa still hanging over the edge to keep the merman still enough to be worked on — and really, they only manage it when he drifts back out of consciousness five minutes into the whole ordeal, falling limp against the glass.

In those five minutes, Denki realizes three crucial things:

Firstly, no, merfolk don’t understand Japanese. As the only one not in the tank in some capacity, he mumbles reassurances through the glass, watching the alien face on the other side contort with all manner of pain and panic. It’s only when Aizawa snaps at him that Denki falls silent and watches with a sense of helplessness.

Secondly, the merman has a surprising number of natural weaponlike advantages, and doesn’t hesitate to use them. Even with Aizawa holding its jaw shut and keeping those terrifying teeth away from the three in the tank, it turns out that mer have literal claws for nails and the stiff sections of their fins are sharp enough to cut if touched the wrong way. That’s to say nothing of the six feet of muscle in the tail, which Bakugou fights to keep pinned against one wall with a grimace. Those handling him will all need a few bandages from the first aid kit, judging by the yelps and swearing.

Thirdly, this mer is, more specifically, a siren.

There’s a moment near the end of the struggle that even minutes later Denki only remembers through a cloud of fuzzy feelings; Yamada had finally captured both the merman’s wrists, allowing Uraraka to move in and do a cursory check of the wounds. Denki recalls its face then, ear-fins pressed back and dark sclerae visible all the way around lavender-pink irises. With one desperate yank, its jaw came free of Aizawa’s grip, and—

let go - settle in - fall asleep - drown - drown - drown

“No you don’t, goddamn trench gremlin, let them go— fuck, Hizashi, stand up!—Hizashi!”

There’s a renewed series of splashes and Denki feels the glass shudder against his cheek. His cheek? He blinks and finds himself pressed to the tank, then pulls away to see Bakugou, Uraraka, and Yamada all pushing their heads back above water with wet coughs and gags. The two around his age look dazed and bewildered, but Yamada stares at his husband and chokes out, “Never thought I’d experience that again!”

Aizawa’s too busy strangling the siren to reply. 

When the creature finally falls unconscious once more, everything goes much, much smoother. Denki’s no doctor but he helps clean and bandage the bite on Bakugou’s shoulder, then fetches an armload of towels. He drains most of the worryingly brown water from the tank and replaces it with fresh intake, listening to Yamada and Uraraka discuss merfolk biology in low voices.

Five minutes later, Uraraka pulls herself from the tank. The question Denki’s wanted to ask since spotting the body on the rover’s feed pushes itself past his lips at last: “Is he going to be okay?”

She gives him a slightly-frazzled half-smile. “Honestly, Kaminari, I’m not sure whether to treat him like a human or like a fish! He’s relying on gills right now, but for whatever reason, he also has dormant lungs, and... I usually only have to account for one or the other when it comes to anesthetic, you know? And on top of that, my normal patients don’t have fingers to tear off bandages with!” She worries her lower lip between her teeth, then laughs. “He’s right in front of my eyes, and I still can’t believe what I’m seeing.”

Denki looks past her to the prone purple form, stepping closer to the glass once again. Out cold, with relaxed features, the siren’s face made a breath catch in his throat. High cheekbones with small scales speckled across them, a smooth jaw, strange dark lips parted to show only the tips of pearly triangular teeth. Even the mottled skin reminiscent of bags under his eyes feeds into the otherworldly visage unlike anything else Denki has seen.

Pushing his own bangs back from his face with a sigh, Denki murmurs, “He’s gorgeous.”

“Isn’t he?” Uraraka pulls her wet hair back into a short ponytail. “Professor Yamada said that’s part of a siren’s danger. And that song of his… I’m going to grab some MS-222 and pray that we can keep him out that way. You and Bakugou don’t need to stick around for the surgery. I’m sure you’ve got work you need to get back to!”

Denki checks his phone. It hasn’t even been an hour since he first spotted the siren. He can’t even imagine busying himself with anything else at the moment.

Yet Yamada still hurries him out of the room as soon as Uraraka returns with the anesthetic, suggesting he take a breather and grab a bite to eat, because the siren isn’t going anywhere anytime soon and is in good hands. Yes , he can come back later, but please keep it hush-hush for the time being, alright?

Which is how he finds himself sitting in silence in the mechanical bay with Bakugou, neither of them more than a few bites into their sandwiches, unable to focus on his literal job in favor of staring blankly at the floor.

“What’s all the secrecy for, d’you think?” he finally works up the nerve to ask the other blonde. “I mean, this is big , we might be the first to see a live mer in centuries, shouldn’t we be celebrating the fact that they’re not all gone?”

Bakugou doesn’t respond at first, brows knitted. After nearly a minute, he growls, “You know there’s more than just magizoologists and historians on board, yeah?”

“Well, yeah.” RV Shinkai Maru isn’t anywhere near the largest ship in the agency’s fleet, but there’s at least a dozen established researchers and instructors and roughly the same number in interns. And that’s not counting the support staff like himself and Bakugou, responsible for keeping the marine technology working. The three-month expedition to study the ecosystem and history of the Ogasawara Plateau had drawn all sorts of interested parties. Including questionable outliers like Yamada’s husband, who Denki’s still convinced is neither a scholar nor scientist, but whatever.

Denki vaguely remembers some of the other professionals on board from boarding day a few weeks back, but their names and studies are all muddled in his brain. He likes to stay out of their way for the most part. He’s never had much to contribute to the kind of conversations they steer him toward, unlike Professor Yamada, who is as easygoing as they come. 

“I’m not sure what you’re getting at,” he admits at last, smiling in apology.

Bakugou rolls his eyes. “Why’m I not surprised? Listen. For someone like the parakeet, who focuses on the history of the fishfucks, it’s in his best interest to get along with the purple asshole and find a way to earn their trust, right? Because the fish-people ain’t stupid, there’s no way they don’t know we’ve been looking for them. So they’re staying away for a reason. He prolly wants to release the fish as a show of good faith or some shit. Repair the relations for the long run.

“But then you got some people on the ship who would give an arm and a leg to study a live fishfuck, keeping him in captivity ‘cause that’s the only way they could stop ‘em from pulling another vanishing act. Worse, some are here for the rumoured dormant ley-line under the plateau. They’re magic-hungry and their sponsors have deep pockets. Who’s to say they won’t jump at a chance to use the purple fuck to find it? You know what the parakeet always says.”

Denki swallows. “Magic calls to magic.” He looks down at his hands. “I guess I get it. But I find it hard to believe that anyone here would lock him up like an animal.”

“Well, believe it,” Bakugou counters, swinging out of his chair and stalking to the door with hands shoved deep in his pockets. “To some people, they are animals.”

Denki lasts an incredible four hours before his mixed curiosity and anxiety demand he go back and check on the siren.

To his surprise, Bakugou is just leaving, and casually tosses Denki a key as he passes. “Fitted it with a new lock. Don’t fucking lose it, Creaky.”

Denki sticks out his tongue at the other boy’s back and bends his left knee; okay, the support brace is getting a bit noisy again, but he’s pretty sure Bakugou would stick to the nickname whether it was well-greased or not. He puts it on his mental to-do list and makes his way inside.

It’s slightly more organized than earlier, with a better path laid out and a space cleared for a table and chairs. A small blue radio is playing—perhaps unsurprisingly—old recorded episodes of Yamada’s Mic at Seaside Radio , which creates a cheerful atmosphere that’s very at odds with the rest of the room. 

The siren is, as expected, still in the tank (Denki adamantly refuses to think of it as his tank, as that would imply some sense of belonging there, which doesn’t sit at all well in his gut). He’s partially suspended in a medical hammock, just as unconscious-or-asleep as he’d been when Denki left. Now, however, there’s large blue plastic patches across the mer’s chest and abdomen, covering the stitched wounds. 

Yamada and Aizawa are off to the side at a large folding plastic table, and not wanting to disturb their discussion, Denki shuffles his way to some of the plastic chairs nearby, only just able to hear what’s being said. Yamada gives him a short smile and wave, likely pointing out their guest, and both straighten up.

“So I think it would be best if we keep him onboard for a while,” Aizawa drawls.

No. No no no. Denki lurches up again, ignoring the stabbing pain in his heels. His conversation with Bakugou comes back in a rush. “You can’t!” He swallows when Aizawa raises a thin eyebrow at his outburst. “I-I mean. He’s not an animal, you can’t just cage him and study him and--”

“Oh, Kaminari, no,” Yamada says, voice gentling. “That’s not what Shouta is suggesting at all! Neither of us want to see him as a captive. It’s…” he looks at his husband. “...for his own safety. And somewhat difficult to explain...?”

“Try,” Denki snaps back. “Please.”

To his surprise, it’s Aizawa who sighs and waves him over to the folding table. A partial map of the Pacific is unfolded, marked with the major local trenches and the Nanpou Islands. A red sticker marks their current location on the Ogasawara Plateau. There’s also a strange white object not unlike an arrowhead, sharp on one side, which Aizawa retrieves and holds up between them.

“First of all. This was found lodged next to a rib inside one of his wounds. It’s likely the only thing that stopped him from bleeding out before your camera picked him up.” Up close, the polished stone—or is it shell?—looks sharp enough to cut, like a fragment of a knife. “It’s part of a weapon, not unlike the kind that have turned up in past archaeological digs at known merfolk civilization sites like the one we're parked over. And, by extension, it implies not only that there are others in hiding, but that he was involved in a scuffle that should have killed him.”

“That’s not too hard to follow,” Denki says. Fascinating and worrying, yes, but complicated? Nah.

“I would hope not. But mer don’t attack their own without trial, and on top of that, there are no modern settlements on the plateau—it’s not a matter of them being hard to find, they just don’t exist. That’s why Hizashi’s here. To study the history of them in the area.”

He can’t help it. “And you?”

Aizawa’s gaze narrows. “Irrelevant to this explanation. As I was saying, mer are no longer here. So our friend in the tank must have drifted while injured - from the south, with the current. Our guess is from one of the trenches.”

A wisp of a memory, foggy but still there, hits Denki—’ No you don’t, goddamn trench gremlin, let them go’— and he frowns. “But you knew that earlier, didn’t you? Back when he had us under his song.”

It’s just a flash, but he swears Aizawa’s features pull into something resembling alarm for a split second. “You—hm. You weren’t underwater,” the man grumbles slowly. He glances over Denki’s shoulder and makes a sour face. “Yes, well. I had my suspicions. Sirens in our waters historically kept near trenches.”

It doesn’t feel like the full explanation, somehow, but the dark expression on the man’s already-intimidating face has Denki dropping that line of questioning. “So you want to keep him on the ship because it’s far from his home?” Then more of the puzzle pieces clicked. “Oh. And he might not be welcome back.”

Aizawa gives him a long, tired look. “I’ve no intention of keeping him for an extended period against his will. He’s not a prisoner. But first he should heal where nobody else can take advantage of his current state.”

Denki nods, but can’t push away the nagging worry at the back of his brain as he turns and looks at the stunning, sleeping creature in the tank. And then what?  

He rubs at his arms, a nervous habit, and approaches until he can lean against the glass. It’s cold and uncomfortable but grounding, in a way giving more substance to the seemingly impossible last few hours. 

It’s almost silly, he thinks, how terribly concerned he is for the mystical figure within, who is no doubt far stronger and more capable than Denki himself. Strange, how attached he is to the wellbeing of this stranger he’s never shared a conversation or meaningful exchange with. Pitiful, how desperately he wants for the siren to open those beautiful, alien eyes, and be okay.

He’s pulled out of his thoughts by the scrape of a plastic chair on the ground right beside him; Yamada had carried it over. The man grins. “You look like you’re going to stick around for a while. Best to be comfortable doing it.” Then he holds out a hand. “Can I give you my number? I’d like to know when he wakes up, and it will save you having to search the ship for me again.”

“Uh, y-yeah, that probably makes sense,” Denki mumbles, handing over his phone on the ‘new contact’ screen. He’s quiet while the information is entered, repositioning the chair so he can tilt his head back against the glass and use the light from the tank to do his work. Before the men reach the door, he speaks up again. “E-even if he has nowhere to go... I don’t want him to be stuck here, or studied. That’s…” he swallows. “That’s wrong.”

Yamada smiles at him warmly, eyes crinkling and almost teary as he nods. Aizawa huffs out something that’s barely passable as a laugh. “Kid,” he says, turning away. “We’d never let that happen.”

Denki wakes up to the sound of his workbook sliding off his lap and slapping the floor.

The radio’s still going, but now there’s a light blanket draped over his shoulders which he’s confident was not his doing. He shrugs it down around his elbows and leans forward. On a second plastic chair beside him sits a covered plate of food and a pink sticky note that reads ‘Some nourishment for the ship’s best babysitter! (•̀ᴗ•́)و  -O’.

He rubs his face and laughs, arching his back until it clicks pleasantly. Of all things to bring him closer to the others on the expedition, he wouldn’t have expected a mythical creature to do the trick. 

Speaking of. He lets out a breath and glances over his shoulder into the tank he’d been sleeping against so soundly.

And is met with a pair of open eyes, lavender on black, and an otherworldly face less than a foot from his own.

Chapter Text

Denki startles violently, lurching away from the glass.

“O-oh fucking heeelllllllllllo, hi there buddy, alright wow yes hi.” He puts all of his functioning brain cells to work on simply not falling out of his chair. His heartbeat hammers at top speeds, a conflicting blend of panic and awe zipping through his veins.

Having also recoiled several inches at Denki’s flinch, the siren watches at him warily, upper lip drawn back over predator’s teeth.  His ear-fins flick and pin back, shoulders rising  and tail lashing against the far side of the tank with a resounding thud. The medical hammock, still fastened on one end, rips and drifts listlessly towards the tank’s filter; when it brushes the siren’s side, he jerks away and an unmistakable wince crosses his face.

Denki struggles to his feet and backs up hurriedly. “Hey, hey, no, it’s fine, you’re fine, I’m sorry I just wasn’t expecting—” He swallows. Sure, the fella can’t understand him, but there’s something to be said for tone and body language, right? He clamps down on the shrillness in his voice, forcing it to steady. “Look, see? We’re good, you ‘n me. Let’s just take deep breaths—or, um, whatever it is you do with gills—and neither of us freak out so you don’t aggravate that side of yours.” He dons a toothy smile, then thinks better of it and closes his lips.

After the surgery one of the others must have finished filling the tank to the standard capacity to give the siren more room. Now, as the long-bodied figure looms in the upper half of the enclosure’s waters and glares down, torn fins flaring out like the corners of an extravagant cloak, Denki feels smaller and less impressive than ever before.

“Y-you’re incredible,” he mumbles. The hair on his arms stands on end. “Like, damn. You can’t understand a word of this but I want you to know I’m… I’m on your side, as much as you’ll let me be. Which is probably not at all, considering, well.” He waves vaguely at the tank, swallowing. The siren is still guarded, which twists Denki’s innards with guilt, as if this whole situation is his own doing.

And really, that’s not too far off the mark, is it?

He rubs at his arms, but still can’t bring himself to look away. At least his rambling seems to have eased some tension from the other being. Those stunning eyes, while still filled with distrust, are scanning him up and down and flicking around the room.

Denki chuckles weakly. “Yeah it’s… nothing special, sorry. I don’t think this room’s been used yet this expedition as anything other than storage, but you’re safe here. At least until we can release you, which we are going to do as soon as we can, once you’re, uh. Once you’re better.” He motions to the blue plastic bandaging on the siren’s chest, then pats the same place on his own. “How’s it feel?”

The siren lays a hand over the bandage with a scowl and angles that side of his body away from Denki, gaze narrowing. He doesn’t make any move to tear it off, though, which alleviates some of the concerns Uraraka had expressed.

Oh—he was supposed to alert the others when their patient woke up, wasn’t he? Denki pats his pockets for his phone, then spots it clattered on the ground near his workbook, along the base of the tank.

Hm.

The others can wait a bit longer.

“I’d ask if you have a name, but I doubt that’ll get me very far. Maybe I should ask Professor Yamada if he has any texts I can borrow? But for now, uhh. Den-ki.” He points to his chest. “Den-ki. Denki.”

In a kinder world, maybe the siren would now be trying to imitate the sounds like a curious toddler. But in reality, Denki’s just given an increasingly suspicious look before the siren starts tracing the edges of the intake vent, trying to wedge the ends of his claws under the frame.

Denki hobbles forward again, one slow step at a time. “Aw, don’t take that apart, my guy, I can’t get in there easily and you’ve already done a number on Bakugou’s patience. And it’s either this tank or you working out those lungs you apparently have and chillaxing out on the floor, because there’s nowhere else we can put you where you’re safe from prying eyes, y’know? The others onboard won’t have as much reason to question why we’re bringing buckets of fish in here or anything either, as compared to like, the barracks. Wait, do you even eat fish? Was that insensitive? I mean I don’t know what other options you’ve got down there, and with chompers like those, er…”

He trails off, having earned the siren’s attention once more. Over the years, many people have groaned, rolled their eyes, or snapped at him to shut up—Bakugou even throws wrenches—so Denki’s aware that his word-vomit style of rambling isn’t for everyone. It’s just as much of a nervous tic as it is an excited one, and right this moment it could easily fall into either category.

So when the merman’s expression morphs into one of exasperated perplexity—a response so wonderfully familiar —Denki flushes pink and bites his lower lip in a failed attempt to stop the gooberish grin that pulls across his face. He covers his mouth at the last minute to hide his teeth, which only serves to make the siren look even more confused.

Then Denki gets yet another shock when the siren opens its mouth and murmurs back.

His language is like the sloshing of a stream over river rocks, filled with warbles and hisses and clicks. It’s a short phrase, whatever it is, muted by the water and tank wall separating them. But the smooth, deep voice washes Denki with shivers and sends his pulse thrumming once again.

He limps forward, fingertips dropping from his face to press gently at the glass. “So freaking cool.” Then he taps his chest again insistently. “Den-ki. Denki. That’s my name. Denki.”

The siren sinks down to almost eye-level and keeps watching, thick tail coiling against the back wall of the tank. The wariness hasn’t left his features but it’s less acute then before, evident only through the shallow squinting of his gaze.

“We’re gonna be bros, just you wait,” Denki says. “I’ll keep you company and talk your ears off ‘til you get better! O-or until you’re sick of me, er, whichever comes first. I still gotta work but I can get away with doing some smaller projects in here, and… oh! Man I’ve got so much shit that’ll blow your mind! Then you can say you met this cool human dude and—” his smile falters. “And, well, that’ll be that.”

That’ll be when the siren disappears beneath the waves again, possibly cutting all contact with humanity for another century or more. And that’ll be when Denki loses his ‘best babysitter’ status and goes back to being the expedition’s more forgettable technician, unable to speak a word about this whole experience.

Guhh.

He only realizes he’s chewing on his lower lip when the siren moves closer and stares curiously at his mouth. Denki’s about to stop when the other opens his jaws—but there’s no aggression to it.

The siren runs a purple-grey fingertip along the points of his own fearsome teeth, poking out from behind dark lips. It’s almost as if he’s… comparing them.

A thrill comes over Denki and he grins again, this time not hiding it. This is wild, what they’re doing—such a simple exchange of information, and yet it feels like so much more. “Shit, yours are way better! I’ve only got a few sharp ones but they’re wimpy in comparison. And one’s chipped, see?” He holds back his lip briefly, then laughs. “I, uh. I fall down a lot. Gravity’s a bitch. I’d say legs are overrated but my sample size has left me a bit biased, it’s hard enough to climb the stairs to the mess hall most days.”

The siren squints back at him, mouth quirked to the side, fingers curling against the glass. The guy may not be a conversationalist, but at least he’s a good listener... even if the words only come across as meaningless babble.

Denki finger-guns at him to battle back the mild disappointment. It earns another confused look.

When his phone pings, both of them flinch, and Denki snatches it away from the base of the tank. It’s only one of his gaming buddies sending a meme, but it works well enough as a reminder. “Here I am running my mouth when there’s others that might know a bit more on how to talk to you, jeez. If I’ve been stumbling my way through with one social faux pas after the other, I am so sorry, for real.”

He pulls open the contact for Yamada Hizashi and starts the conversation:

The reply is almost instantaneous.

Denki glances up at the siren, who is watching the phone with rapt fascination if the slow spreading of his ear-fins is anything to go by. He desperately wants to pull up a YouTube video to see the sea-dweller’s reaction to moving images, but shelves that for later. 

For now, he’s internally mulling over the best way to herald the others’ arrival. Sure, it’s silly and illogical, all considering, but whatever. He settles on pointing to the door and gestures a ‘come here’ motion at it, keeping eye contact with his companion.

Not moments later, it creaks open. In the brief pause where Denki turns to look, there’s a quick splash, the merman propelling himself away with tension lining his frame once again.

"Hey, no, it's okay my dude, they're good," Denki says, leaning into the glass with a sigh.

From across the room, he hears Aizawa mumble to his husband, "Kid's still trying to make fruitless conversation, I see..."

But Yamada isn't paying him any mind, staring past Denki with a near-reverent smile. “Oh my stars! Look at you." His voice is softer than Denki's ever heard; he slowly approaches the tank with his hands low and palms open, facing forward. "Strong one, aren't ya, to be moving around like that so soon? You'll bounce back from that injury in no time. But what did you get messed up in that put you in our path to start, huh?" 

Denki raises an eyebrow at Aizawa—You were saying? —to which he recieves a scowl in return.

When he looks back into the tank, he finds that the siren's gaze is jumping between all three of them, but unquestionably resting the longest on Denki's—as if looking for answers. 

"Looks like you two hit it off well," Yamada says, but this time he too is facing Denki with a curious grin. "Nothing wrong with that. If his fin and horn development progress are to be believed, you're in the ballpark of the same age! Or... same stage of maturity, at any rate." He winks, and Denki's about to ask what that means when the man casually slings an arm around his shoulders and grins at the siren. "You must be getting hungry! Don't worry. Kaminari's going to stick around for a little while longer, isn't he?"

Denki nods quickly. "Y-yeah, of course."

"Great! Fantastic! What better way to bond than a shared meal, right listeners?"

Aizawa trudges to the base of the tank stairs, ignoring the warning hiss from the other side of the glass, and drops a bag near the bottom step. It squelches upon hitting the ground. 

He then meets Denki's gaze. "Well, kid?" Denki swears there's a hint of a smirk on the dark-haired man's lips. "Suppertime. You're up."

Yamada throws his head back and cackles.

Denki regrets everything.

Chapter Text

Denki’s been an advocate against stairs of all kinds for over half a decade now, but rickety metal steps that clang with each footfall have always been on his shit list. Add a pit of water to one side—complete with a wary being capable of mind control—and suddenly he’s sure that there’s a serious Health & Safety violation complaint to be made here.

His leg braces may be advertised as lightweight, but he still struggles with each step, leaning heavily on the questionable railing opposite the tank. He takes some solace in Aizawa’s presence only a few steps behind him, close enough to prevent him from tumbling the dozen-odd feet to the floor. Or into the tank itself, should the siren get any ideas. Still, they’re putting a great deal of faith into his donned life jacket, he thinks.

Denki casts a glance into the water; a long purple blob sits on the opposite side of the tank. The merman’s eyes seem to glow, cutting through the green-brown seawater from a distance. Watching.

Taking a deep breath, Denki tosses down the cushion Yamada had provided and carefully lowers himself onto it, one leg over the top step and the other bent awkwardly in the direction of the tank. This leaves enough room for Aizawa to lean over him and drop the duty bag on his other side.

Then the disheveled man abandons him, returning to where Yamada is sitting near the table to watch the whole affair.

(“You’ve managed to build the most trust with him,” the researcher had said, when Denki first protested the additional duties of his babysitter designation. “If I go up there he’ll have me in that tank in an instant!”

“What about Mr. Aizawa?” Who should have been the first choice, in Denki’s opinion, what with his inexplicable resistance to the siren’s song.

Yamada’s wide grin had flickered almost imperceptibly towards a grimace. “Falling in the water would be even worse for him! He reacts to the salt dreadfully, even in short doses.”

Denki looked at Aizawa, who must have heard, as he lifted one arm with an irritated sigh. The arm that he’d plunged into the tank to steady the siren’s jaw – now covered in bandages from finger to elbow.

Well, crap.

“Okay,” Denki said, swallowing. “Fine, I’ll do it.”

“Atta boy, Kaminari!”)   

Now, he shakes his head and reaches for the zipper to the deep blue bag, dreading the contents. He feels like a horror movie protagonist as he pulls it slowly down the row of teeth…

Seaweed.

That was the squelch.

“You guys did see his teeth, right?” Denki mutters just loud enough to reach the men sitting more comfortably below. But he’d spoken too soon; next to be revealed is a plastic container filled with foot-long slices of meat, and beside that, an entire softshell crab. “Is this really the kind of thing they eat?”

“Well… not exactly,” Yamada chuckles. “But we’re in no position to fetch deeper-sea eels and crustaceans. So local substitutes will have to do! It won’t do him any harm. Truthfully, he could likely even stomach many surface foods without issue – but I daresay that’s beyond his trust.”

Denki pulls some of the stringy seaweed out and looks around for somewhere clean to set it. He finds none.

Scowling, he calls out, “Man, I’m not just tossing this into the tank. That’s hella rude. Is there something down there I can use as a plate at least?”

As Yamada scouts around through the mess of objects in storage lining the walls, Denki peers into the water again. The siren has inched closer with Aizawa’s departure, but is staying safely under the surface. Those piercing eyes track the bundle of seaweed curiously.

“If this was dried, I’d be all for it, my dude,” Denki says with a laugh. “Little bit of rice, some choice salmon and roe and dipping sauce—mmm. Don’t think I could stomach it like this. I’ve got a low tolerance for food with the consistency of wet rubber.”

“Ah!” Yamada exclaims. “Will this do?” He brandishes a blinding-yellow foam kickboard.

“Better than nothing,” Denki agrees, catching it when it’s tossed. He dusts it off with his sleeve and settles it in his lap, then places a wad of the seaweed to one side, aware once again of the siren’s gaze on him. “Prepare to be blown away by my unparalleled plating skills,” he jests, making a show of arranging the aquatic plant in half-hearted spirals. Then he reaches into the bag for the crab.

Halfway to the kickboard, it splays its legs all at once - and Denki flings the still very goddamn alive what the fuck crab with a shriek.

It hits the water with a small plop , and then there’s a rush of movement and a crack against the glass below that shakes the stairs. Denki glances into the water and first sees only an array of purples, until he spots two strong hands, holding—crushing —the twitching crab against the side of the tank.

The siren’s face turns upwards, meeting his stare, and Denki sucks in a quick breath because holy shit he’s so close, within an arm’s length, so vibrant and wild and… dangerous. All the siren has to do is reach up, and…

“Back up, kid,” Aizawa calls out, likely on the same train of thought.

Denki lurches back from the side, sitting once again against the railing of the stairs, trying to calm the frantic stuttering of his pulse. He holds the kickboard between them as if it could offer any protection.

“Y-you could have warned me that it’s alive,” he gasps out, then corrects: “Was. Was alive.”

“As I understand, it moving should have been warning enough,” Aizawa drawls back. “If you weren’t distracted trying to impress your charge, perhaps you would have noticed that.”

Denki’s ears burn at Yamada’s subsequent hyena-laughs, and he pettily turns his back to the men, trying to salvage his pride simultaneously with the skewed seaweed pattern on the kickboard.

He twitches when the tip of two horns break the surface a few feet away, followed by the upper half of the siren’s face, forehead plastered with wet aubergine locks. Those dark sclerae make it look like the mer’s lavender-pink irises float in ink, and give an impression of pinpoint intensity far beyond anything a human could muster.

“S-sorry, uhh,” Denki says, re-balancing the makeshift plate. He eyes the dangling crab body clutched in the siren’s hands. “Don’t worry about giving that back, I’m not sure it’ll add much to the plate at this point.”

The foot-long slices of eel meat are, to his surprise, cooked – much the same as he’s used to finding in his own dinners. He’s not actually sure what eel looks like raw, especially not the deep sea varieties, and the merman looks mildly wary of it. Denki places two of the sticks on the board regardless.

Then, very carefully, he leans over just enough to place the floating ‘plate’ on the tank’s surface, and taps it gently in the siren’s direction.

“Bon appetit, buddy,” he mumbles with a nervous smile.

The other drops back below the surface.

Denki thinks, for a moment, that despite his best efforts he has royally fucked up and managed to offend the guy. He’d practically chucked half the meal at his charge’s head with a banshee scream, after all, and can’t begin to imagine what kind of interpretation was made from that. He’s got an apology ready to roll off his tongue when a clawed, webbed hand slides over the opposite side of the kickboard and drags some of the seaweed back down under.

He leans back with a relieved sigh. Done and done. His own stomach gurgles weakly, but least he wouldn’t be responsible for starving a beautiful, mysterious mythical creature. “Is my meal from Uraraka still down there, or should I resign myself to his diet, too?”

Aizawa fetches the prepared human-food plate, and for the next half hour the room is surprisingly peaceful. Denki lets his mind drift to the tank filter’s low humming and snippets of murmured conversation down below. When gentle snaps and crunches start from within the tank, he adamantly looks away and sets aside his own plate with a grimace.

The cooked eel, however, remains untouched. The next time Denki sees the grey-purple hand feel across the surface of the board for seaweed, he grins. It’s all gone – save for the stuff still heaped in the duty bag – and when the siren’s head finally breaches it’s all he can do not to snicker at the way the mer glares at the offending meat.

“C’mon, give it a try! May not be as slimy and alive as you’re used to, but it’s really good, promise,” Denki assures him. When the siren doesn’t react to that—because really, why would he?—Denki mimes picking it up and taking a bite, then smiles theatrically.

The siren squints at him, and roughly nudges the board back toward the stairs. Seawater sloshes over the meat as it bobs its way back over.

Denki sighs and unzips the bag—

take it – bite –

He tastes salt and smoke, wanting to gag at the unexpected food on his tongue but not able—

chew – swallow

He’s aware of his teeth gnashing the eel meat that the siren has fed him with Denki’s own hands, and as cloudy as his brain feels, each thought struggling through fog, he’s distantly grateful that the merman has taken his stubby grazer’s teeth into consideration.

Denki feels himself swallow, and his mind clears.

“Uurk,” he groans, wiping away the salt water and juices on his chin with the back of his hand. “No, buddy, no. That wasn’t very cool.”

A squeeze on his shoulder alerts him to Aizawa at his side, looking equal parts irritated and concerned. “You good, kid?”

Denki slaps the eel slice back down on the kickboard. “Just dandy. Would have been nicer with rice. Or if it wasn’t drenched,” he grumbles. He tosses the makeshift plate back into the tank, glaring at the partially-surfaced mer, who doesn’t look apologetic in the slightest.

However, as he watches, a hand slowly snags the bitten slice and drags it down.

When the meal is over, the siren resurfaces, seemingly content to listen to Denki talk. And Denki does talk, explaining the purpose of the expedition and what kind of duties he has, recounting the first time he’d controlled the rover and how mind-blowing and unnerving he’d found the vast open world beneath the waves.

He chatters about his coworkers and the interns he gets along with; of how Bakugou threatened to toss him overboard on an hourly basis the first week, until they learned each others’ boundaries and Denki realizes that giving Bakugou the larger-scale engineering jobs was easier on the both of them. He laughs about Uraraka slowly claiming parts of the mechanic bay as a place to relax and talk shit at Bakugou; the two of them are practically competitive about it.

Denki’s met a few of the other interns at mess, too, and counts the names he remembers off on his fingers. Yaoyorozu, working on her Theory of Magic doctorate, Kouda and Tokoyami, in zoology, Iida in history. Then he recalls one of the interns he remembers on the basis of dislike: a loud Applied Magic student who’s always showing off and badmouthing the magically-inept—Denki’s somehow managed to avoid his jeers thus far.

He’s not sure how long he goes on; time falls away, and it’s surely getting late. His back and hips start to ache from the cold, tough metal behind and below him, and he adjusts his position with a wince. He’s not doing his already-fragile lower joints any favors sitting up here when there’s actual chairs down by Yamada and Aizawa.

His left knee spasms when he straightens it across the stairs, telling him yeah, it’s time to get down.

“Gonna get to ground level and then we can continue this fantastic dialogue, alright?” he says, easing both legs around.

The siren drifts closer, still submerged from the nose down, and slowly curls the fingers of one broad hand over the edge of the tank. His dark claws click against the glass, and the sound casts a shiver down Denki’s spine.

“Erm, Mr Aizawa? Could I get a hand down, please?” It’s not that he’s afraid of the siren, per se—he’s moderately confident that the big purple fish-guy means him no harm—but everything about him screams ‘predator’, and some primitive instinct is currently reminding him that there’s a reason so many old tales end with sailors becoming ill-fated playthings.

When Aizawa sighs and gets up, Denki gently lets his feet drop a further step down, and eases himself to an unsteady stand.

don’t go – stay with me – turn back – come here –

The cloudiness in his mind is brief this time, because it is interrupted—

By pain.

He’s yelling even as he comes out of the trance, facedown against the metal grill of the stairs. His shins throb and burn and feel like they’ve been smashed to pieces all over again, even as he casts a glance over his shoulder and sees that they’ve just hit the steps at a terribly unfortunate angle where the braces couldn’t protect them.

He leans into where one step is biting into his hip, trying to shift the pressure away. He should have just waited for help to come to him, should have ignored his flight response—they’d been doing so well.

Aizawa curses, hands held out awkwardly as if unsure of where to put them. “What can I do, kid?”

Denki chokes on a gasp and blinks to clear his eyes of unshed tears. Hopefully the men wouldn’t think any less of him for it; this fucking hurts. He struggles to turn over so at least it’s his back to the stairs. Everything feels broken, but he’s pretty sure that’s just his abused nerve endings causing a fuss. It’s not the first time this has happened by a long shot, but it’s one of the more painful ones in recent memory, for sure.

Seeing Aizawa still watching him for an answer, Denki flushes. He knows the help he needs, but it’s never goddamn easy to ask near-strangers to literally pick him up.

The man seems to understand it without words, though, and nods before getting an arm under Denki’s back and thighs. For someone so visibly unimpressive, the man has more muscle than Denki had mentally credited him with. Aizawa huffs and barely breaks a sweat as he navigates them down to the floor.

A long purple tail slides into view over his shoulder; the siren is drifting close to the other side of the glass, ears pinned and wearing an expression that looks surprisingly like regret. 

Denki can’t quite manage the reassuring smile he tries to fake.

He’s not entirely certain what the overgrown fish had meant to do, after all; he doesn’t remember feeling any particular impulse to jump in the water, just a forced desire to turn around and sit down near the edge, where the siren had perched mere feet away. It had been a distinctly different feeling to the drown command that morning. 

Black claws scrape gently against the inside of the glass. The siren’s chest contracts and something akin to a chirp echoes softly through the room, followed by few sounds that roll from that sharp-toothed mouth like a trickling stream.

Denki blinks. “Huh?”

“He’s sorry,” Aizawa mutters.

“Oh.” Then, “Wait, how do you—”

He’s settled carefully into one of the chairs, even though Aizawa’s expression implies that the man would rather drop him. “With that hangdog expression, it couldn’t be anything else.”

Okay, fair point. He smothers down the flash of anger, looking away from the siren. He gets enough pitying looks from people on a regular basis, people who actually understand what an inconvenience he can be. He dreads having to deal with it here, too.

“Hizashi went to get some ice. Do you need to see the ship doctor?”

Denki looks at his legs and carefully feels them down to the ankle; they’re marked up badly, but most of the damage is old scars and new swelling. The bruises will come later, and they’ll be terrible, but nothing’s broken.

“Nah,” he mutters. “I’ll be fine. I can walk.”

“Right.”

To prove a point, Denki grabs his cane and leans heavily onto it, staggering to his feet. Invisible knives dig in at his ankles and just under his knees, but he’s had worse, he’s pushed himself through more than a few bruises for the sake of his dignity.

“Fine,” the black-haired man relents, though he still doesn’t look convinced. “But when Hizashi comes back, I think it would be best for you to let him help you to your room.”

Denki nods jerkily, and spots his workbook on the floor near the tank, where it had fallen what feels like so long ago now. He grimaces, not due to its placement, but rather due to the shadow cast over it from the concerned mer in the tank. Apparently ignoring him for a minute or so wasn’t enough to make him lose interest.

He sighs and makes his way over. 

Purple-grey palms come up against the glass as Denki bends over, almost losing his balance again. He gives a small smile and looks away—

“Den-ki.”

It’s quiet, muted by water and glass, but unmistakable. Caught by surprise, Denki blinks and raises his sights to the siren’s face. 

Dark lips form the same chirp-shush-cluck apology from minutes prior. A claw draws a ‘u’ shape from the inner corner of one eye, down around the cheek to the top of his cheekbone. The gesture’s meaning isn’t clear, but that’s not the important thing right now.

Denki swallows, a more genuine grin pulling across his face without his consent as he struggles to fight down the squeal of he was paying attention back then, he knows my name!  

But the siren still looks unsure, as if waiting.

“It’s-- it’s okay, buddy. You’re forgiven. Just… no more trying to make me use limbs that you don’t have yourself, huh? If we’re drawing lines for what we’re not okay with, that’s a good place for me to start.”

He hopes he can repeat that in a way that can be understood before anything else bad happens; for now, his new friend looks guilty enough that Denki doubts it’ll be an issue anytime soon.

The siren floats closer, at eye level once more. For a brief second his gaze flits over Denki’s shoulder to where Aizawa is milling about by the desk on his phone; then he leans in and taps the pad of two fingers against the glass near Denki’s chest.

“Den-ki,” he repeats, before splaying one hand over the base of his own neck, over his collarbone. What he utters then sounds like a string of soft shushes and a click, like the push and pull of a tide on sand. It’s long, five syllables at least if Denki’s parsing it right, but somehow, unquestionably, he knows it’s a name. The siren repeats it once more, expression determined.

Denki’s breath hitches. “Shee… Sheen-souhee… uh. Tohshee?” He can’t quite get the silky curves of the sound right, the cadence of the name foreign on his tongue. It’s almost definitely awkward and comically off like those videos of Americans stumbling through Japanese, but the corners of the siren’s lips quirk up and his eyes burn violet, encouraging. 

“Sheen-souhee-tohshee. That’s—you, wow. That’s your name?” He presses his fingers against the glass as he does so, mirroring the siren’s earlier gesture.

Vivid violet ear-fins spread and flutter gently, and the smile the other wears widens a fraction.

Giddy, Denki beams.

He wonders if merfolk distinguish given names from family names, because there’s certainly enough syllables to make that work. Maybe he’s not even breaking up the sounds correctly, if they’re meant to be broken up at all. “Can I—can I call you Tohs… er, Toshi?” Heat rises to his cheeks, which is silly, but it feels like he’s asking to use a given name and maybe that’s wrong of him to hope or pretend they’d be close enough for that one day, were this at all a normal situation. Bah.

The siren tilts his head, contemplating it, before responding with a minor amendment. God, everything sounds so much better coming from him.

“Hitoshi?” Another flutter of the siren’s ears. Denki supposes that must mean approval, and makes a mental note of it. “A-alright! Hitoshi. Wow.”

The room’s door creaks open; it’s Yamada, back with a pack of ice and… a familiar wheelchair. Spotting him, the blonde man half-smiles. “I encountered Bakugou on the way and asked him what might make you most comfortable. He said you left this in your workspace for when things got particularly bad.” The smile falters. “Did I… overstep?”

Denki shakes the instinctive grimace from his face and pushes away from the tank, more aware than ever of the shooting pains up his calves now that the rush of excitement is petering out. “No, that’s… probably a good idea. Thanks, Professor Yamada.”

He limps halfway to the chair before turning back. 

Hitoshi is drifting near the far side of the tank, seemingly caught in a glaring match with Aizawa. His attention snaps back to Denki the moment his hand rises, but the expression on the siren’s face has returned to neutral and unreadable.

“I’m coming back tomorrow,” Denki promises, for what little good his words do. “And the next day, and the next. I know you don’t understand me right now, but we’ll make it happen.”

He doesn’t see the knowing wink Yamada sends Aizawa, nor the defeated head-shake made in reply.

Chapter Text

As soon as Hizashi leaves with the technician kid, Shouta closes the door, breathes an irritated sigh, and turns to the tank. He’s waited over three-quarters of a day to get a moment alone with the siren, and now that the only one due to walk back in is his husband, he can finally take his chance. 

He stalks over to the tank’s control panel—feeling eyes on him—and activates the divider panel. The tank’s warning lights flash orange as an extra wall of glass begins its ascent in the middle of the tank, evenly bisecting it.

The young siren spits all sorts of curses and rude titles at him, but Shouta ignores that for now.

When he approaches the stairs to the tank, the brat does as he’d expected, fleeing to the opposite side of the divider before the new wall prevents him from doing so. It would be funny if not for the way the other’s ears are low and flat with fear. Shouta does his best to be non-threatening as he strips off his pullover. His undershirt and sweatpants can stay; Hizashi will know to bring him something fresh, he hopes.

Then, after a moment of consideration, he pulls off the bandaging on his left arm. Beneath, slate-gray skin and scales mark him like an accusation, like a fraud. He scowls at the sight, but the rest of him is going to match come the morning, so there’s no point making a fuss right now.

And when the dividing pane of glass reaches the top of the tank with a drawn-out beep, Shouta inhales deeply, forces it back out, and lets himself drop into the captured piece of the sea.

His body has gone so long without adjusting that at first everything burns . He shuts his eyes to defend from the saltwater and covers his mouth to stop himself from habitually relying on lung-oxygen. When nothing fixes itself within a few moments of submersion, a twist of dread works itself through his system; has it been too long? Has his body forgotten? Has he locked himself into—

A set of underused muscles on either side of his neck flex, nearly-invisible flaps of membrane pulling away with the movement, and finally Shouta can breathe.

In the back of his mind he feels the itch signalling that the brat is Singing at him, a desperate bid for control now that Shouta’s in the water, where the Song works strongest. Smart kid, he thinks, if a bit oblivious. He’ll let the little one off the hook for not noticing his gills due to the billow of hair currently obscuring his neck.

The other’s panic is almost palpable when he realizes the Song isn’t working. ≈Why won’t you listen? Get out and go take a dive in a vent, you squid-haired, gazer-faced, finless twit!≈

Shouta tries to blink open his eyes, and ends up squinting - they still sting. The young siren is against one of the far corners of his side, teeth bared and sporadically hissing as if he’s not capable of suppressing the reflex. Gods, the little asshole is as noisy and flighty as a coral mer, for all he looks and Sings like a trench-dweller.

≈You’re going to drown yourself, stupid walker, and your pod will blame me!≈

It takes a surprising amount of effort for Shouta to readjust to vocalizations without air. It really must look like he’s drowning at first, his lips and throat and chest all contracting in sequence while he figures it out.

The brat lets out a sharp bark. ≈Get out— ≈

≈Ca— ergh. C-Calm down, you guppy,≈ Shouta finally answers. ≈I’m not at risk of drowning, but I’ll make note of your clearly genuine concern.≈

For a long few moments, nothing interrupts the slow bubbling of the tank’s filter. The young violet trench-dweller is still as stone in his corner.

Then, in monotone, ≈What.≈

Shouta grips onto one of the handles embedded in the back wall, using it to anchor himself in place. Two minutes wouldn’t be enough for the sea’s magic to change him - hell, two hours wouldn’t be enough - so he’s gotta make do with this uncomfortable barely-transitioned state. He curses, but it’s Japanese and comes out garbled with all the wrong sounds.

He’s already lamenting his decisions. Can’t even sigh underwater in any way that feels natural and refreshing. ≈Your shock disappoints me.≈ He raises his slate-skinned forearm, black scales glinting over his knuckles, and scratches idly at his sparse beard. 

There’s another extended beat of silence. ≈But. You’re a walker. You have walker-limbs.≈

≈Legs,≈ Shouta corrects absently, and he really does not want to go into the hows and whys of that right now. So he redirects. ≈Come on over here before you barnacle onto the glass. I’m no threat to you.≈

≈...Bullshark.≈

Shouta’s brain whirrs blanks. Did he just? Was that…?

≈Please tell me that’s not mainstream trench slang these days,≈ he grumbles. ≈Now, come here. We’re just going to talk.≈

The young one hunches, hesitating. 

Shouta wants to bash his own head against the floor, repeatedly. Perhaps he could learn a thing or two from the small mechanic’s patience. ≈You see this wall? I don’t have the means to break it. And even if I could and did, my teeth are walker-flat and my claws nonexistent. You have nothing to be afraid of.≈

≈I’m not afraid,≈ the mer mumbles, and finally floats closer to the glass. His gaze jumps between Shouta’s arm, pseudo-gills, and legs with confusion, but he still seems averse to speaking his mind.

So Shouta starts again. ≈What do you go by?≈

Violet eyes narrow at him. ≈You first.≈

≈Very well. Call me Aizawa, as your walker friend does.≈

Surprise touches the kid’s face for a flash—as if surprised Shouta had actually given an answer—then his lips twist. ≈He uses ‘Hitoshi’ for me.≈

And it’s Shouta’s turn to be taken aback. The young mer gave away his name to a human already? It hasn’t even been a full day! Even if ‘Hitoshi’ is only a fragment of it, harmless and unevokable, that’s a shocking offer of trust to a non-mer. The tiny blonde’s probably clueless.

Judging by the intensely defensive look on Hitoshi’s face, he knows as much. Shouta wants to groan and chastise the kelp-for-brains for his impulsiveness, but holds back. He’s not the kid’s sire, and doesn’t want to risk damaging their current fragile peace by acting like one. So he shoves back those instincts and resigns himself to a shallow nod.

≈Alright. I can tell you have questions, Hitoshi, and I hold a few of my own. So I propose we trade, back and forth, answering truthfully. Is that acceptable?≈

Hitoshi nods.

Aizawa swipes some of his drifting bangs out of his eyes. ≈Good. You may go first.≈

≈What are you?≈

Really, he shouldn’t have been surprised, but Aizawa had been hoping that self-preservation instincts would have struck up something more like Where am I? or even What are you going to do with me? — something important. He’d forgotten how insistent merfolk curiosity could be towards new things.

≈A lorekeeper of sorts,≈ he answers evasively, knowing that’s not what the kid had meant. ≈Plus a husband, a shoddy cook, and an individual cursed to be dragged along into complicated situations. Anything more specific is too difficult to explain to you at the moment.≈ He leans back against the glass. ≈Why were you exiled?≈

Hitoshi jerks back as if stung, face scrunching up with anger. ≈How did you—≈

≈I’m not unfamiliar with the laws in the trenches, little fish. Your injury was at the blade of another mer. You were cast out.≈ His voice softens more than he’d intended. ≈So, why?≈

The siren’s mouth is a straight, hard line for a solid half-minute, one hand coming up to cover the blue bandaging. Finally, he grits out, ≈I made a proposal that the wrong person overheard. It got back to the leadership. They called me a critical risk to their ‘peaceful’ way of life.≈ Then he sneers. ≈If by ‘peaceful’ you mean dismal for anyone lower-caste.≈

Lower-caste? Sirens had always been an inherently competitive, sly, and ambitious lot, some even harbouring malicious streaks towards humans and other mer. But Shouta doesn’t recall caste divisions; prestige was gathered in trophies and hoards. Even the more aggressive deep-dwellers would go out of their way to ensure the wellbeing of their own kind. It was ingrained in their magic, wasn’t it?

Hitoshi’s follow-up question makes Shouta set that aside for later consideration. ≈How do you know so much about us?≈

Shouta resists rolling his (still-stinging) eyes. What a fin-biter. Little shit’s getting specifically personal with his questions; that’s fine. He can play along and still keep to truths. ≈My partner is a walker lorekeeper who specializes in studying mer history and culture. I myself have an interest in protecting some of that knowledge from being lost, but also from falling into the wrong hands. I know a thing or two more than most walkers about sea magic.≈ He scratches his gray forearm idly. ≈Also, you are not the first siren I have met.≈   

Perhaps that last was a bit too much; Hitoshi’s eyes narrow in suspicion. ≈What? How—≈

≈I believe it’s my turn,≈ Shouta interrupts, and the young one’s teeth click together irritably. ≈What was the proposal you made that caused all of this?≈

≈That… we reclaim and rebuild the plateau’s reef.≈

Shouta frowns. ≈Trench sirens would be out of their element so close to the surface.≈

≈Yeah, obviously. That’s the point. I wasn’t suggesting it to the sirens.≈ He pauses, looking miserable. ≈It was to the corals and their kin.≈

Ice-cold distress shoots through Shouta’s veins, all at once. ≈Coral-fins,≈ he repeats slowly. ≈Living in deep-sea trenches?≈ 

Hitoshi shrugs. ≈Where else were they supposed to go? Your first siren must be a self-centered pufferfish type to have not mentioned them. Not surprising, though. Most treat corals and mixed-bloods like bottom-feeders.≈

The lower-caste are corals . Old guardians of the plateau’s ley-line, most slaughtered like farmed fish over a century ago. 

There are coral-fins living among the sirens.

Hizashi, he thinks, we finally found them. 

And hopefully it wouldn’t be too late.

≈...You still in there?≈ Hitoshi mutters, shaking Shouta from his shock. ≈I asked—≈

≈How many got away? How many are left?≈

Hitoshi’s eyelids droop, and in monotone, he mimics, ≈ ’I believe it’s my turn.’ ≈

Little shit. Shouta waves him on impatiently.

≈I asked where we are right now. Did… did I beach?≈

≈No. Your new walker friend found you with one of his devices; you’re on a ship.≈ But Hitoshi wears an expression of blank-faced unfamiliarity. What are they teaching the small ones down there? ≈A… walker-carrier that travels on the water. We’re still out at sea.≈ And, as it’s going to come to light one way or another, he adds, ≈Currently anchored over the plateau.≈

Lavender-on-black eyes widen, then the young siren responds like a lightning strike. ≈There’s two dozen pure corals left. Around a quarter that in mixed-bloods, though sometimes it’s hard to tell ‘til patterns come in.≈ Barely a pause. ≈Have— have the walkers found...≈

When he doesn’t finish the statement, Shouta takes a guess. ≈The heart of the ley-line?≈

Hitoshi’s ear-fins flare in confirmation.

≈They haven’t. Why?≈ 

And though it seems that the young guppy is trying to remain calm, Shouta can read him like a book; the fidgeting of excitement and worry and stress all clear. Try as he might to hide it, there’s hope in Hitoshi’s eyes.

It echoes the inexplicable hope that had surged through Shouta a month ago, when he insisted to Hizashi that they return to the plateau after all these years. It matches the thrumming in his veins, the whisper at the back of his mind, calling him to this graveyard of arcane energy he’d avoided for so long.

He pulls his hand away from where it had moved to rest over his heart.

Hitoshi watches him with a contemplative gaze. ≈You... feel it too, don’t you?≈

≈I don’t know why, or what it means ,≈ Shouta hisses back.

≈Isn’t it obvious?≈ There’s a crooning wistfulness to his voice now. ≈It’s almost ready. The ley-line is going to Sing with new magic again, after all this time.≈ He raises his gaze. ≈And I’m going to protect it.≈

In any other instance, Shouta might have laughed at such a bold claim, but the familiar conviction in Hitoshi’s voice leaves him without a slick retort. 

He is reminded of another, from long ago. A boy with a sky-blue body and pale, glittering fins; a cloud of white hair like an undersea flame; a blinding smile full of mischief and determination. You were always saying the same thing, he tells the memory. Didn’t I call you a fool, then?

Through the water and glass he hears the click of the door; Hizashi steps in, spots them, and offers a subdued smile. For a moment Shouta even sees him as they’d all met back then: a storkish blonde human, terribly loud, who could sing the stars from the sky without a pinch of magic to make it happen. 

Surely enough, his husband has a change of Shouta’s overclothes draped over one arm. Hizashi mouths, ‘Almost done?’

His chest aches with century-old nostalgia, but he nods and pushes off toward the wall by the stairs.

Hitoshi’s claws click against the glass behind him. ≈Wait, that’s it? You’re not going to tell me I can’t?≈

≈Why would I do that?≈

The question catches Hitoshi off guard. ≈B-because I’m mostly siren?≈

So the kid’s one of the mixed-bloods he’d mentioned, for all he doesn’t look anything like the light-colored reef-dwellers Shouta remembers. Figures. ≈I think that if the coral-fins’ numbers are as low as you claim, they’re going to need all the help they can get to keep the ley-line safe. Regardless of species.≈

He takes satisfaction in the surprised chirp the young one lets out, and almost, almost manages to grab the lip of the wall when he’s called for again.

≈H-hold on! Sosvii Aizawa.≈ The title of respect for adult mer catches Shouta by surprise; given the embarrassed darkening of the young siren’s face, it was probably accidental. ≈What’s going to happen to me?≈

Ah, there’s the question the moron should have asked first. 

≈You’re going to stay in here until you’re healed enough to swim and defend yourself. And you’re going to stop Singing at my husband and the other walkers while you’re at it. The trick you pulled earlier could have gone much worse.≈

Hitoshi’s face slackens. ≈Denki. Is he alright?≈

≈He says he’ll be fine, and I trust his judgment. But that’s not all.≈ He turns fully to face the siren. ≈I’m going to be clear with you, little fish. This setup is barely keeping you a secret as it is. And when walkers get injured in what should be a safe environment, questions get asked, and you’re ultimately only putting yourself in more danger of being found out.≈ He blinks slowly. ≈Not everyone on the ship would agree to let you go free.≈

Hitoshi slowly sinks to the floor on his side with wide eyes. ≈But you do?≈ he says quietly, almost like a plea. ≈And Denki? And him?≈ He gestures to Hizashi.

≈Yes. You can call him Yamada. We’re here to help you, Hitoshi.≈

The siren does not respond to that.

≈Get some sleep, guppy. If you need anything, ask me — but not where your friend can hear it.≈

Hitoshi’s ear-fins flare again, wordlessly.

So Shouta pulls himself from the tank, and mentally prepares for a day of hibernation in his sleeping bag, waiting for his slowly-forming gray-and-black patterning to once again fade away.

Chapter Text

Denki hobbles through his morning routine the next day with an extra dose of vigor, eager to go see Hitoshi as soon as possible. His plans are defeated, however, when he swings by the mechanical bay and a broken sonar component sits waiting for repairs on his desk.

He gives Bakugou a pleading look.

“Fuck no,” the other blonde grunts back. “While you played mother hen to an overgrown fish yesterday, I had to deal with some dumbfucks crashing a seafloor sweeper into a wall they ‘couldn’t see’. Prolly just too busy staring at a goddamn scribble on the ground to watch where they were steering. You’re getting off easy.” He jabs his thumb towards a messily-punctured sweeper. “That’s my project, you shit.”

His piercing glare says the rest; Bakugou had willingly took on the larger task.

Denki clasps his hands in a praying motion, murmurs, “You’re the best, man,” and promptly sits down to work.

Three hours later, he finally gets to the tank room. Yamada is trying to reassure Uraraka, who has donned a wetsuit and is wringing her hands nervously just inside the door.

“Yeah, there’s our golden boy!” Yamada practically shouts upon seeing him. “Great timing. Kaminari, how do you feel about being a peacekeeper today?”

“Uuuh?”

“Professor Yamada says the siren trusts you,” Uraraka explains. “When I go too close to the tank he gets defensive. And after yesterday… well. Without Mr Aizawa here, it doesn’t feel like a smart idea. His only memory of me is also of being afraid.”

Denki blinks. “Where’s Mr Aizawa?”

Yamada claps a hand on his shoulder. “Staying in bed – not feeling quite himself today. But no reason to worry! I’ve already fetched your aquatic friend’s meals.”

“Hitoshi,” he murmurs back. At the pair’s confused looks, he shrugs. “His name is Hitoshi. Er. Sorta.”

Uraraka’s expression brightens in interest, but Yamada positively beams.

“Wow, Kaminari!” the former laughs. “You two really must be on good terms. He’s moving fairly well, but I need to change the bandage to make sure. Think you’ll be able to help?”

And that’s how he finds himself perched at the top of the stairs once again – albeit this time with more cushions to save his back and legs from further issues.

To his glee, Hitoshi doesn’t hesitate to swim right over, fingers curled over the lip of the tank. His hair droops over his face when he surfaces to his neck. The raised scales that speckle his cheekbones and forehead, ranging from lilac to dusky violet, glint under the light like embedded jewels. Denki wants to reach out and run his thumb across them.

“Hey buddy. Hitoshi.” He leans over his knees with a grin, which the siren subtly returns. Denki points to the bandaging on Hitoshi’s chest, over his lower right ribs. “How’s that holding up?”

Uraraka joins him then, kneeling at his side and giving Hitoshi a smile of her own. “Hello!” she chirps, unbothered by the mer sinking so only his appraising eyes and above remain surfaced. She puts her hand over her collarbone, as Denki had shown her. “Uraraka!”

Hitoshi’s ears flare, if briefly. Above water, they’re a dazzling mix of hues, even more spectacular with their translucent areas backlit.

“That means something like affirmation, from what I can tell,” Denki explains. “Okay Hitoshi, Uraraka—” he gestures to her to make the point extra clear, “—is the one who fixed you up.” He waves towards the bandaging. “She’s going to get in the tank… with you… and check your injury. Yes?” He charades what he can of the statement, Uraraka laughing under her breath with every movement.

But Hitoshi doesn’t acknowledge the statement with any sign of approval. Instead, one scale-spotted hand slides over the edge and comes to rest on the upper arch of Denki’s foot, clawed fingers and thumb settling feather-light against his ankle.

Denki’s mental track stalls, skips; He’s touching me. Sure, literally everyone else on the ship with knowledge of Hitoshi had beat Denki to the ‘physical contact’ milestone within an hour of saving the injured mer, but this is different, right? He reached out first, he wanted contact. He’s touching me.

Maybe he should be concerned that he can be tugged into the tank with minimal effort from this position, but damn. It’d almost be worth potentially drowning.

Unable to stop himself this time, Denki drops a hand and runs his fingertips across the back of Hitoshi’s knuckles, where his skin is decorated with sparse scales. His whole hand is eerily cold—which makes sense for a deep-sea dweller, he supposes—and almost fake-feeling because of it.

“Um, Kaminari?” Uraraka mumbles, interrupting the moment. Her cheeks are pink and Denki’s certain his are the same, if for completely different reasons that he doesn’t want to unpack just yet.

Right. He’s supposed to be getting her in the tank, not feeling up the hand of a pretty merman.

Hitoshi squeezes his ankle lightly, like a question.

“Ah… it can’t be me,” he tries to explain, wondering what kind of gesture he can give for this that won’t be taken as a rejection. He points back and forth between himself and the water, shaking his head. “I can’t go in the water, bud, I’m sorry. Tank’s too deep for me to get out, and these aren’t waterproof.” He taps a nail on the dark metal of his leg braces. “And I haven’t got the medical training she does, but… dunno how to act that one out…” he trails off.

Hitoshi’s eyes jump between the metal bands circling on either side of Denki’s knees, attached along the sides with sturdy rods and screws. His curiosity apparently wins over cautiousness because he rises out of the water enough to reach the lowest section of the brace, halfway up Denki’s calf. He slowly scrapes the deadly points of his claws across them, soft but deliberately, as if studying the material.

Denki stays stock-still as the reverberations from the act shiver through the metal and onto his leg. He’s traced the bands so many times on his own before, so it’s not an unfamiliar sensation. And somehow this is different enough to make his insides twist with anticipation.

But then Hitoshi sinks away and stares at Uraraka expectantly.

“Is... is it alright if I come in, then?” Her smile is still nervous.

This time, Hitoshi’s ears flare.

They spend a few minutes draining the tank down to a low setting again, Hitoshi looking more and more miserable as he rests along the bottom. With only five feet of water he’s forced to extend lengthwise to stay fully submerged. When they’d first put him in the tank yesterday, with levels this low, it hadn’t seemed quite this stuffy. Hitoshi being awake and clearly uncomfortable made all the difference.

Then Denki watches, with no small amount of envy, as Uraraka slips over the lip of the glass and plunges into the tank. Her hair billows momentarily before she finds her footing and stands.

Next to Hitoshi, she’s so small. Even though just yesterday Denki had stood beside the tank parallel to the siren, it hadn’t been enough to truly appreciate the size difference; Hitoshi rarely stretches out straight. Now, he floats near the surface on his back, chest and abdomen bared to the marine vet. He’s long and lean even before factoring in his tail, with thick deltoids and a pronounced collarbone. The drawn triangular build of his upper body looks straight out of a pro swimmer commercial, and jeez, why did Denki’s brain care about this now?

When Uraraka leans over the siren, fingers pulling gently at the edges of the bandaging, Denki catches Hitoshi’s gaze and immediately forces himself to turn his attention away. He feels his face flame and does not want to explain the reason for it, thanking whatever deities would listen for keeping Uraraka’s attention otherwise occupied.

The last thing he needs is for the others to know he’s attracted to a guy that’s half fish.

It’s not like he’s surprised, when it comes to the waist-up portion of his aquatic friend. In that regard, Hitoshi is very objectively good looking and anyone who would deny it, regardless of sexuality, is a total liar, he thinks. Even the siren’s face and its mythical features—horns, dark sclerae, scales—have an unconventional, foreign beauty to them that Denki finds himself entranced by.

His brain still isn’t sure what to make of the tail and the fact that Hitoshi is technically always naked, but hey, Denki shouldn’t be bashful on the other guy’s behalf.

And hell, he’d love to ask what the touching earlier had been all about. Is personal space usually so quick to disappear between merfolk, or is Hitoshi… acting out?

…Flirting?

(It can’t be that, no, because give it a week or two and those wounds will be healed and the incredible, breathtaking siren will be out of his life forever.)

He’s dividing up Hitoshi’s food onto the swim board when Uraraka gasps. Denki checks back in on them in an instant.

“Is this normal for you…?” she asks in a wondrous voice, hands splayed on either side of the wounds. But they’re barely wounds anymore: just long, shallow gashes, dark as if bruised, indented as if someone had his scraped skin away with a bread knife.

Even Hitoshi at first appears mildly taken aback, but the expression rapidly fades into one of realization—and if Denki’s reading the sudden sharp grin right, excitement. Hitoshi twists his midsection experimentally but stops after a moment with a wince.

“You’re not entirely healed,” Uraraka tuts. The way she puts her palms on his chest to hold him steady hits Denki with yet another zap of jealousy, and he shuffles where he sits, working to keep it off his face. Uraraka pulls her hands away, oblivious, and continues. “Still, this is incredible progress. Your magical nature comes with some fairly nifty perks! You’ll be fully healed in no time – I can’t wait to check in tomorrow!”

Denki’s stomach sours further. In no time, huh?

Uraraka calls for the tank to refill, Yamada acknowledges with a shout of his own, and shortly the water level begins rising back up to full capacity.

Feeling like rocks have settled in his gut, Denki strips off his socks and shoes and hangs his feet over the edge. The chilliness of the sea makes him flinch when it reaches his toes, but he doesn’t pull back. Then the water laps around his heels, then up to his ankles. The valve shuts off partway up his calves—just below his braces.

He’s never been scared of water; he’d learned to swim just fine as a kid and was pretty decent up until the accident. Even then, trapped and broken and in the dark, the sound of the tides was all that kept him sane from the belief that he was never going to be found. The sea had saved him, hadn’t it?

He blinks the creeping memory away and flexes his toes in the salt water.

Next to him, Uraraka braces her hands on the wall and pulls her upper body out of the water with several strong kicks until she can maneuver to sit on the edge. Her cheeks are extra-rosy from the cold but she’s smiling, laughing to herself even, as she brushes her damp fringe aside. It’s only when she catches Denki’s expression that her own falters.

Oops, must not have been hiding those meddlesome emotions too well after all. He leans back on his palms with a sigh.

“Kaminari…” she starts, in the soft, pitying kind of tone that he hates.

But before she can say anything more, another pair of hands brace on the tank’s edge—one on either side of Denki’s spread knees—and there’s a surge of purple—

Hitoshi leans over him, propped up by strong, corded arms, and Denki forgets how to breathe.

The siren’s hair drips across Denki’s lap from how he’s angled into his space, and below the stairs his tail thumps against the tank wall to keep balance. His navel and hips are slotted between Denki’s knees, showing off the smooth transition from skin to scales.

And it’s a lot of skin, because he is right there, staring down from less than a foot away.

“Hi-Hitoshi,” Denki stammers in what’s nearly a whisper, caught frozen like a rabbit. His heartbeat’s so loud that it would be a miracle if the other couldn’t feel it somehow. “What—?”

Hitoshi must find his balance because he eases back a fraction, shaking his head to get his hair from his eyes. Once free from the weight of the water some strands curl up and others stand nearly on end, giving the mer an increasingly wild look, only helped along by the triumphant, challenging edge to his lilac gaze.

His chest is still though, Denki’s notes; he’s not using his lungs, and his vivid gills lay mostly-flat against the sides of his throat, filaments twitching as they try to steal oxygen from the air but fail. It’s got to be uncomfortable – why doesn’t he inhale? Has he never learned to do so before?

The siren seems almost expectant, borderline frustrated, but Denki cannot for the life of him figure out why.

Uraraka scoots backwards with a grin, fiddling to work down the zippers of her wetsuit. When Denki looks over she practically coos at him. “Isn’t that sweet, Kaminari? You won’t go down to him, so he came up to you!”

But it appears to be a bit of a struggle for him; between his inability to breathe and the way he winces—right, that injury hasn’t gone away—Hitoshi probably can’t last holding himself up like this for too long.

Denki slowly straightens, aware that now he’s the one crowding space, but the siren doesn’t seem bothered in the slightest. In fact, when Denki awkwardly holds his hands between them (what is he supposed to be doing? What’s being asked of him??), Hitoshi’s aural fins flick forward then fan out wide. The display brings to attention the numerous subtle differences in color within, like a beautiful abstract painting, or a bouquet of flowers.   

Despite the cold water dripping across him and the chilly arms framing his legs, Denki suddenly feels unbearably warm.

A laugh bubbles up from inside of him, genuine and bright, and before he can stop himself he’s lifted his hands to those fins. “Show-off,” he murmurs with a smile. He gently drags the pads of his thumbs across the webbing, feeling it twitch under his touch, even as Hitoshi keeps his face still. It’s thin and rubbery, translucent near the outer edge and brilliantly speckled with a dozen hues of purple towards the skin. Further up, the fin has a stiffer build, the way it overlaps on itself almost featherlike. Denki brushes his fingers over those sections, fascinated.

And if he hadn’t been so close, he might have missed it: a strange low trill that pulls from deep in Hitoshi’s throat. It’s brief, a few seconds at most, before Hitoshi jerks back an inch with wide eyes. The siren blinks, lets out a choked-sounding chirp—then he’s shoving off the wall and surges back into the tank with a splash that soaks Denki to the bone.

“Okay then,” Denki sighs as Uraraka howls with laughter.

Even when Denki ‘serves’ the food onto the kickboard and places it on the water, Hitoshi doesn’t come back up again, for whatever reason adamantly submerged on the opposite side of the tank.

Yamada is smirking when the two of them finish descending the stairs. “We’re gonna get you in the water next time, Kaminari!” he jokes. “Poor Hitoshi looked about ready to beach himself to please you, didn’t he?”

Denki’s ears go pink yet again. “I-I don’t even know what he wanted - and I think I upset him.”

That makes Yamada falter. “What makes you think that?”

“He made this… sound?” Denki shrugs. “I don’t really know how to explain it, Professor. Like a low buzz and— what?”

But the man spins away, hand over his mouth, stalking towards the tank. Denki can’t see his expression but he does see Hitoshi, who reacts to Yamada with flat ear-fins and a scowl.

“Say, Kaminari. You have overcoat canisters for the rovers and other devices down in your work bay, don’t you?”

“Er, yes?”

Yamada turns, grinning. “Any vapor barrier types among them?”

“Yeah, of course.” Those are arguably the most important; salt water’s quick to eat through metal that spends a lot of time submerged in it. The vapor barrier coatings help devices keep their integrity—

Oh. Duh.

The professor props his hands on his hips. “So, if I were to ensure you’re safely able to get in and out of the water, and move around within it when necessary, would you be up to taking the plunge?”

“Yes,” Denki breathes as quickly as his mind can parse the question. “Of course, I don’t know how I didn’t even consider before—it’ll take a few coats, so many little parts I’ll have to do separately and put back together but— but yes, yes I definitely— I could probably be done for tomorrow—”

“Then let’s plan for that!” The bright man looks like Christmas has come early; why he’s excited for the prospect, Denki can’t imagine.

So he falters. “But, sir. Why...? I can’t offer any skills to help him...”

“Kaminari. You want to spend time with Hitoshi, don’t you?”

Is that even a question? “Y-yes.”

“And he wants to spend time with you?”

He thinks to yesterday, when the siren had accidentally tripped him just to stop him from leaving, and all of the little touches and actions today that seemed to have the sole purpose of bringing them together. “I… think so?”

Yamada nods. “Lastly, what do you think the objective advantages of a close bond with him might be, once he’s released?”

Denki thinks harder on that one. He remembers Bakugou bringing up a reason for earning Hitoshi’s trust - so that the researchers could keep some sort of connection to the mer and not lose them for another century or so. To find out why they’ve been staying away.

But he also doesn’t think that’s the only answer.

“He doesn’t have anywhere else to go,” Denki mumbles at last. “If he trusts me, then… maybe he’ll let me help him. I don’t know how but — I feel like he knows he’ll need it.”

He’s important to me, he doesn’t say. And I want to be important to him.

Yamada looks pleased. “That’s as good an answer as any, listener! And with that settled, I’ll make sure we have the means to get you navigating the water in short order!” he winks.

With renewed excitement, Denki hobbles to the tank, tapping until he has Hitoshi’s attention. The siren looks hesitant to even glance in his direction at first, still half-scowling, his face-speckles seeming more vivid somehow— but he does finally meet Denki’s stare.

“Tomorrow, Hitoshi,” Denki promises, getting a confused fin-flick in response. “Tomorrow.”

He does the first coating before bed, but stays up late into the night, remembering their closeness with a lightness in his chest.

Chapter Text

The expeditioners who keep breaking their equipment must be conspiring against him, judging by how efficiently they keep him supplied with small tasks the following morning. Bakugou’s on his day off, so Denki’s left to handle it all. It’s a stroke of luck that he’d gotten the second coating done on his braces before the workload piled on. When he’s finally able to escape the workbay it’s well past noon.

He’s taken aback to find the full count of secret-keepers gathered around the table in the tank room. Unease settles in his gut, but a quick glance to the tank itself assures him that Hitoshi is alive and well. 

“Took your goddamn time,” Bakugou grunts.

Normally he might meet that with a quip of his own, but right now the mood in the room is too distracting that the only words he can bring forward are, “What’s... going on?”

For a moment nobody seems quite sure how to answer that; Denki looks from Aizawa, who has a heavily-bandaged neck, to Uraraka, half-out of a sopping wetsuit, and finally to Yamada. The lanky blonde grins but it doesn’t quite reach his eyes.

“Well! There’s some good news, some bad, and some… perhaps a tad borderline. Subjective to opinion. Which would you like first?”

The agitation inside Denki grows, unfurling like cold tendrils through his limbs. He swallows. “Let’s start with the worst and rise from there.”

Yamada waves him over to a seat, between himself and Aizawa. Denki sits stiffly.

“So,” the professor starts with a short sigh. It’s unnerving to see him so muted. “When all of this happened, we never properly booked this tank for our use. And without a good reason for why a historian would need such a thing, I didn’t do that after the fact, either.” He drums the fingers of one hand against the back of the other. “A request for access was placed this morning by the biology team - we can’t contest that. Even the lock change went under the radar. If we push back, it will only raise suspicions.”

Denki’s mouth is dry. “Okay,” he says, swallowing. Then, logically—

“Which brings us to the middling news.” There’s that smile again, with traces of a grimace. “I was able to hold them until tomorrow morning, citing a need for time to get my research papers and exhibits organized! We’ve still got the rest of the day, little listener. Nobody outside this group is any the wiser about Hitoshi, but…” He must see Denki’s realization written on his face, voice faltering and forced smile receding. It turns apologetic.

“We’re releasing him tonight,” Aizawa finishes gruffly.

Tonight.

Denki slowly leans back in his chair.

Tonight. That’s it, then. 

Just yesterday he’d been counting down in terms of weeks, not knowing for sure, but definitely not expecting the siren’s wounds to close up literally overnight. Surely Professor Yamada or Aizawa would have known something more about this rapid healing? They are the experts. They could have said something. Could have stopped him from—

— From what?  His devil’s advocate bites back. From getting attached? That’s all on you, dunce.  

“The good news is that he’s all healed up,” Uraraka offers helpfully. “From what I can tell, that is. We won’t know for sure until he’s got a stretch of open water to work with. Still, even if it means swimming against a current, he should have no issue getting home!”

She doesn’t know?  Denki catches Aizawa’s eye; the man gives a subtle shake of his head, a warning. So the other two hadn’t been informed of Hitoshi’s predicament. 

“That’s… good to hear,” he says, but his voice sounds dull and unenthused even to him.

“Tch.” Bakugou gets to his feet, storming off towards the tank as if it had personally offended him. “You’re s’posed to get dunked today, aren’t you? Hurry up and get over here then.”

Denki looks up sharply, then glances at Yamada. “It’s still alright—?”

The man’s got encouragement written across his face, even if it’s less animated than the day prior. He settles a hand on Denki’s shoulder and gives it a squeeze. “I think it’s the best idea in the world, right now, listener. For you and him both.” He seems like he wants to say more, but doesn’t.

Denki doesn’t need to be told twice. He lets Uraraka link her arm with his and pull him towards the tank.

He doesn’t have a wetsuit of his own—there’s never been a need, and the full ones are very pricey—but someone has managed to find an upper-body piece in his size to keep his core insulated from the chill of the seawater. Which is fine with him, because he’d already put on swim trunks under his leg braces and there’s zero chance that he’s going to take either of those off in public, thank you very much. It’s bad enough that he has to go topless for even a short while in front of his peers and Hitoshi, all of which (save maybe Yamada) are much more physically built than he is.

And if he’s left pink-faced by the siren’s gaze—intent and never straying as Denki strips off his t-shirt—well, that’s another thing entirely. Uraraka is kind enough to only giggle when Denki fumbles the arms of the wetsuit top, and at last she zips up the back of it without a word. It’s perfectly snug, and the sleek lifejacket he’s handed next fits overtop.

He’d hoped that the silence would extend to Bakugou as well, but maybe that was too much to ask.

“It’s only been two days, you dumbshit,” his explosive coworker snaps, adjusting the chains on the hammock-like seat that’s meant to raise and lower Denki from the water. “Two fucking days, and you’re pining like a goddamn teenager. Over a fish.”

How’s he meant to respond to that? Denki reasons that if the other blonde noticed then it’s a sure bet everyone else has caught on as well. Besides, Bakugou’s not wrong. He swallows. “Aah, well. Yeahhh.” Nice reply there, brain. Thanks for that. “It’s stupid.”

“Damn right it’s stupid.” Bakugou’s checking over the pulley system almost aggressively. “Why’d you let yourself get all twisted up? You knew it’d end with sending him back. Did you fucking expect another outcome?” He then mutters ‘and he’s a fish,’ a bit quieter, still in disbelief over that fact in particular, Denki supposes.

Denki struggles to find words to describe the roiling discomfort in his chest. “....No,” he admits. “Couldn’t help it. I just like spending time with him.” A ball of tightness forms in his throat, and try as he might, he can’t choke the words back. “Tonight’s gonna suck.”

Bakugou huffs, turning his glare on Denki for a long moment as if disgusted even just by the implication of feelings. Then he shakes his head. “For fucks’ sake, Creaky.” He motions to the seat. “Whatever. Get on and go float with your shitty asshole fish crush.”

That has Denki’s heart leaping nervously again—but he obliges as Aizawa joins Bakugou at the makeshift pulley and they bicker quietly over something he doesn’t listen to. Instead, he turns his attention to the tank again.

Hitoshi has surfaced to just above his nose again, staring up unblinkingly. The gentle ripples in the water are distorting the rest of his face, hiding his expression.

Does he know? Had the others found a way to tell him about his impending freedom? The siren’s visible elation the day before about his own healing progress suggested eagerness about getting back to the sea. Surely now Hitoshi must be wondering what they’re going to do with him next; he can’t fault the guy some trepidation. 

Maybe that’s why he’s back to watching Denki like he’s unsure. Hesitating to come close. Or maybe, unlike Denki, the siren was content to be distant now that his freedom was a few short hours away. Please don’t let that be the case.

“So bud,” he says amiably, getting settled. “You’re not gonna try and drown me for real this time, are ya? We’re past that, right?”

It earns a snort from Bakugou, at least.

Then something’s tugged over his hair; goggles? Aizawa sighs from right behind him. “Having second thoughts? Nobody’s making you do this.”

“No,” Denki replies instantly. “I— I really want to. Just… nervous.”

“Just keep your fingers out of his mouth and leave his gills alone. Don’t touch the upper thoracic fin, either—the one below his neck. Try not to bleed. Avoid all that, and he shouldn’t bite.”

“I meant nervous about the water… ”

He hears a chuckle from Yamada down on the floor, and Aizawa grunts. “Hm. Don’t be. We’ll keep an eye on you. Both of you.” The latter is clearly aimed at Hitoshi, and the siren’s ear-fins settle back as if he’d somehow understood.

A minute later, the seat swings out over the water, and Denki is eased down into the tank.

By the time the freezing water is up around his waist, his heart is thundering a thousand beats per minute. Part of it is no doubt the feeling of being trapped, unable to get out of here on his own (—is this what Hitoshi’s been faced with for days? Gods). Another part is because he’s blatantly aware of the long purple tail and fins curling beneath him like a shadow, and the lilac-on-black eyes that haven’t left his face.

Then he’s dropped further, and finds himself stabilized only by the lifevest.

For a moment, when the seat disappears, he flounders. Childhood instincts tell him to kick, kick to tread but he knows if he does it’ll hurt like a bitch. He flails instead, cupping at the water and trying to compensate for the awkward way the lifevest tries to force him onto his back.

Webbed fingers tangle in the vest’s front straps and pull him upright again. 

Wide-eyed, Denki reaches forward instinctively—he grasps onto smooth, cold forearms and sucks in a breath. And just like that, he’s stable. The flash of alarm subsides almost immediately, giving way to relief, and he grins so wide his cheeks hurt at the sight of the siren keeping him balanced. “Hey there, Hitoshi.”

Hitoshi’s aural fins spread wide, his eyes narrowing softly. When he lifts his chin above the water there’s a warm grin curving his dark lips, too. His shark-like teeth flash for a moment. “Denki,” he chirps, low and quiet, just between them.

Whoa boy. Denki inhales shakily, willing his pulse to steady. He slides his hands from Hitoshi’s forearms to his elbows, feeling the skin give way to pebbled scales, and then to timidly settle at the base of the siren’s biceps.

“This is wild, huh? I don’t even remember the last time I went swimming. It’s been years. I was pretty good back then! Maybe not as fast as you, I bet you’re real damn speedy when you get out in the open water.” Then he swallows. In the back of his brain he’s aware that they’re being spectated, so he can’t say too much. Can’t say exactly what’s on his mind. He lowers his voice to a murmur instead. “Hope I’ll get to see that.” His chest aches.

Hitoshi slowly releases the front of the lifevest, giving time for Denki to find his balance. Then the mer sinks beneath the surface. Right, gills. He doesn’t immediately come back up, however, circling below languidly and curiously. Denki feels the tap and scratch of thick nails against the brace-bands on his thighs, then a silken fin drag across the sensitive bottoms of his feet, making him flinch. Just out of his sight thanks to the obnoxious vest, Hitoshi wraps a hand around his ankle, curling and prodding inquisitively.

Don’t pull, please don’t pull, he thinks, still working hard to stay balanced and upright.

Thankfully Hitoshi moves on, sliding his fingers up one calf, brushing over a knee. The siren’s other hand cups the back of it and gently encourages it to bend, testing the unfamiliar joint and bones with near-reverent care. 

Meanwhile, Denki is having an internal crisis, face aflame despite the cold. The mer’s probably clueless to just how intimate the actions are, right? When Hitoshi’s thumb sweeps thoughtlessly over the sensitive inside of Denki’s thigh, it’s all he can do to not jerk and topple onto his back with a squeak. 

Over the sound of the filter, he hears Yamada call out, “Might be a good time to set some boundaries, Kaminari!”

Still being watched. Yup. A glance to the side tells him Bakugou and Uraraka have left, but that doesn’t mean he’s gung-ho for where this is going.

He dives a hand down, finding a billowing mess of hair; his knuckles knock none too gently against a dull-tipped horn. It’s enough to make the hands on his legs pause, then release, as Hitoshi drifts back to the surface, silently questioning.

“Congratulations,” Denki breathes out, hoping he doesn’t sound too flustered. “You’ve discovered legs! Fantastic things, when they work right, but— ah, wh-what now?”

Hitoshi is circling again, but this time near the top of the water where Denki can see. The siren lazily meanders behind him, then around to his other side, fantastically long tail trailing his upper half. Soon Denki’s surrounded by a full loop of dusky-lavender skin and amethyst scales.

And his fins, hell. Denki may have gotten very familiar with the siren’s ear-fins yesterday, but they’re small compared to the soft, sweeping sheets of vibrant color flowing from Hitoshi’s back, sides, and tail. He’s terrified of touching them the wrong way— what had Aizawa said to avoid? The one near his neck? Did that mean the others were fair game, or…?

Hitoshi murmurs something in his odd language, and to Denki the inflection almost sounds irritated—but the siren’s smirking at him. Another statement follows it, shorter, then after a moment of silence when Denki shrugs hopelessly, Hitoshi flicks his ears and takes one of Denki’s hands, settling it firmly over the glittering expanse of scales near the end of his tail.

“O-oh,” Denki peeps. He lets out a shaky little laugh. “Alright, okay.” That answered his previous question, he supposes.

Beneath his palm, the scales are sleek—at least in the area he starts carefully stroking across. But when he curls his other hand to the opposite side, what he assumes to be the rear of the tail, his skin catches on infrequent ridges and raised edges. 

“These ones are spiny,” he says, surprised. They remind him a bit of coarse sandpaper when he runs across them backwards. The pad of his ring finger cuts on one of the scale-teeth and he gasps at the sting. “Shit, should have expected that.” He shakes his hand in the water with a grimace. “You’re really built like a weapon, arentcha?”

But Hitoshi is suddenly tense, staring at Denki’s fingers. His eyes are strange too, like the colors have shrunk small and left more of the void in their place. And he’s so still , unblinking, only his nostrils flaring gently.

“Kaminari, are you bleeding?”

He whips his head around; Yamada and Aizawa are standing at the glass, the latter with one hand on the stair railing and ready to climb.

Oh, fuck.

Without answering he jabs his injured finger into his own mouth, frightfully aware of Hitoshi’s pin-pricked gaze following it keenly. He tastes mostly saltwater, but there’s copper to it, too. 

The siren grabs his hand and tugs, pulling the finger back out. Before Denki can stop him, Hitoshi presses the pad right below the cut—it’s so shallow, barely there—and watches a small bead of red gather at the end.

Shit shit shit. Denki yanks back, but the siren’s grip doesn’t falter. “Stop— p-please—” What had Aizawa said? No teeth, no gills, no neck fin, no bleeding. He’d managed to bungle the last one already and now his hand was getting far too close to the first for comfort. “Hitoshi, please— ”

Something bright and yellow knocks the siren’s head aside with an audible, foamy thud before dropping to float on the water. The kickboard?

He doesn’t have time to ponder it; a deep, guttural growl rumbles out of the incensed mer in front of him, chilling Denki to the bone. Hitoshi’s face is pulled into a terrible snarl, all teeth on display, but he’s looking upwards and over Denki's shoulder.

“Snap out of it!” comes the roar from above, and shit, Aizawa’s got a pair of lungs on him.

Denki’s wrist clicks from Hitoshi’s iron grip, the blood on his poor finger tracking down into a thin line. Thankfully the siren is otherwise distracted, thundering out some incomprehensible remark with hisses and rumbles and clicks. Denki wants to do something, anything to calm the situation down, but his only remaining workable limb is having to compensate for being tugged completely off balance.

Aizawa shouts something else but it’s lost in noise as Hitoshi ducks to avoid another thrown object. Despite the lifevest, Denki is briefly tugged under as well, and comes up spitting salt. 

“Hitoshi,” he tries again, coughing. He finds himself held closer to the siren, which is great for balance but also sucks because it’s like being up against a revving chainsaw. “Mr Aizawa, sorry but you’re just making it worse—”

Breathing heavily, he glances at Yamada through the glass; the man is surprisingly silent. When their gazes meet, something uncertain and apprehensive pulls across the professor’s features.  

Soundlessly, desperately, Denki mouths ‘what?’

Yamada’s eyes flick up to his husband and back, then to Hitoshi, as if indecisive. He closes his eyes for a moment. When he opens them again, a certain degree of confidence is back. He gestures to Denki, taps his forehead, points to Hitoshi, and taps his forehead again.

Alright. Okay. Get even closer to those teeth? Can do, he supposes. Hopefully he’s not misunderstanding the suggestion. Steeling himself, Denki dips further into the water, and gets a better grip on the siren’s shoulder.

Then using the momentum of coming back up and all of the strength he can manage, he lunges up and gets his free arm hooked around the back of Hitoshi’s neck. Denki closes his eyes at the teeth so frighteningly close to his nose, tenses at the snarl, and drags Hitoshi down enough to press their foreheads together.

The noise softens and peters out in a matter of seconds.

“Ohh… oh gods, aha, Shou, don’t give me that look, i-it worked,” Denki hears Yamada warble weakly— and promptly turns his attention away from that.

Because when he opens his eyes, Hitoshi’s own are right there, wide and bright and shell-shocked. Denki pulls back cautiously, waiting to see if metaphorically taking his finger off the magic button is going to revert this peaceful, much appreciated change— but it doesn’t. He lets a relieved grin take over his expression, relaxing against the mer’s torso, out of breath.

Hitoshi’s aural fins slowly spread to their full height and width, and if Denki wasn’t still a bit dizzy from the whole affair he might say that some of the scales on the siren’s cheeks were faintly glowing.

“Time to get out, kid,” Aizawa grumbles loudly.

But Denki pays him no mind, doubly so when Hitoshi’s hold on his wrist loosens considerably, and the mer’s other hand tentatively comes to rest on his hip instead. There’s a moment of tension all around when the bleeding finger is called back into attention, but Denki wills himself not to panic this time as Hitoshi brings it to his mouth.

The siren’s dark tongue slowly skirts over the line of red, leaving a tingling sensation. Denki can feel a shudder ripple through the body he’s pressed against, and holds his breath. But no bite comes; in fact, Hitoshi almost looks nervous himself as he studies the tiny injury. And then he releases the hand entirely.

Denki looks at his finger, perplexed, dabbing the pad with his thumb. The tiny cut’s still there, but coated thinly with a clear layer that’s stopping the bleeding.

“N-noted,” he mumbles, pink and mentally reeling. “Thank you. And I’m— I’m sorry, Hitoshi, I shouldn’t have freaked out. I trust you, I do, or else I wouldn’t have gotten in here, but I guess I thought the warning was real a-and—”

He’s silenced by Hitoshi’s forehead butting gently against his again, and. Hm. Yeah, that’s its own strange but totally valid method of pacifying, isn’t it? He lets go his breath, closes his eyes. Who cares how this looks? Not him. Not right now.

Aizawa clears his throat.

Without missing a beat, Denki smiles. “Nah, sir. I think I’m good right here for now.”

Shouta collapses back into his chair with a grunt, eyes narrowing at his husband.

“I’m not sorry,” Hizashi murmurs, but it’s not convincing. 

He’d been plenty sorry the instant they’d both recognized the single-focus in Hitoshi’s eyes; friends or not, the guppy’s still a bit of a wildcard and Aizawa remembers plenty of young sirens who weren’t able to shake the predator instinct once triggered. Maybe it’s because the little fish is a halfbreed that it worked.

Or, he concedes irritably, Hizashi was right for once.

“Kaminari cares, Shouta. It’s fast and new and probably terrifying, for both of them. You remember what that was like, don’t you?” His husband smiles brightly, if a bit sad in the eyes. There’s so many bad memories intertwined with the good that it’s impossible not to feel everything all at once when they recall those days. “Earlier, when we told him—gods, the look on his face. It was just like…” He shakes his head as words fail to come.

Shouta reaches across the space between them and entangles his scarred fingers with Hizashi’s slender ones. “So he cares,” he admits quietly, watching the pair in the tank cling to each other as the human kid in question rambles on about who-knows-what in an airy voice. “That doesn’t mean he has to know. Or get involved.”

“He’s already involved. When Hitoshi comes back for him—”

“If .”

Hizashi pauses, then laughs. “Shou darling, I recognize a lovestruck siren when I see one. But fine. If Hitoshi comes back for the boy… I’m going to help them. Tell them what they need to know to be ready, to make it work. But I don’t want to do it without your permission.” Then his husband’s clear green gaze falls on him, hopeful. “Please?”

Shouta sighs deeply, rubbing idly at the edge of the bandages around his throat that cover his gills. The whole mess with the ley-line is going to be a pain even without the budding feelings between two lifestyle-incompatible problem children. But it’s the same sire-like gut reaction as before telling him that; he can’t very well tell the little fish how to feel. He’d be a hypocrite of the first degree. 

“Fine,” he murmurs under his breath, squeezing his husband’s hand gently. “If you think it’ll help protect them from everything else that’s coming, let’s do it.”

He can feel Hizashi’s giddiness without looking, the warmth blossoming through his other half at the response. But it’s nothing compared to the overwhelming tidal pull of reassurance that sweeps through him when Hizashi pulls their heads together. Briefly, softly.

Yeah, he thinks, let’s keep them safe this time.

Chapter Text

It takes a good deal of Hizashi’s convincing to get Kaminari out of the tank for good, after a few hours of exhausting in-and-out to give his body the breaks it needed. The last time Shouta pulled him up, the kid’s face was already pinching in that sad way that would no doubt set the tone for the rest of the night.

Even more monumental of a task is getting him to leave for a little while so Shouta can speak to Hitoshi, and communicate what’s going on. The kid’s determination to spend every remaining moment with the siren is a pain in the ass, but on some level, he understands.

That still doesn’t stop Shouta from secretly cranking down the temperature in the room until Kaminari’s teeth are chattering and he agrees to change out of his wet clothes.

“It was the logical option to prevent suspicion,” he says dryly to his husband, who’s also shivering and scowling now that the boy has zipped away. “Keep an eye on the hall?”

When Hizashi scoots out the door, looking pleased to escape the makeshift fridge, Shouta allows himself a smirk. He turns the temperature back to a reasonable level before making his way over to the tank.

Hitoshi wears a dazed, fond smile, which only fades a fraction as he floats down to Shouta’s level. His fins are all still half-flared in contentment. Every line of his body is relaxed and nonchalant, as if Kaminari had been a strong drink, leaving the siren calmer than Shouta has ever seen him. But he knows it won’t be long lasting.

Shouta clears his throat. Vocalizing Mermish sounds above water is an extraordinarily difficult task, complicating further when relying on lungs.

≈We’re letting you go now.≈ Best to keep it blunt. ≈Some of the other walkers on the ship want to use this tank, and we need to get you out before they come looking.≈

Hitoshi stills, the lazy smile slipping as he processes. Then his expression flits between so many others in such rapid succession that it’s hard to keep track. Surprise, relief, excitement—and then it lands on hesitation, ears slowly folding back against his hair. ≈Makes sense,≈ he murmurs back, casting his gaze down and aside thoughtfully. ≈I feel really good. No pain left at all. Guess the ley-line being so close by gave me a boost.≈

≈Mm. You’re going to look for the heart of it, I presume?≈ Of course he was, if his resolve hadn’t dissolved under the human kid’s reverent touches. He watched the siren’s aurals flare in confirmation. ≈Then be careful. Other walkers from this ship are prowling down there with their devices. They got close enough to hit the guardian’s aura barrier yesterday; the sonar didn’t pick it up, obviously. So now they’re asking more questions. If you’re seen, half the rasyakiin ≈ — he uses the word for magic-leechers, those that hunt the ley-lines and steal their power — ≈ stalking the Pacific will be out here within a day, and our goal of protecting it will be hopeless.≈

≈’Our’?≈

≈Yes,≈ he mutters, crossing his arms. ≈Yamada and I have a combined interest in keeping it safe, and we’re going to help however we can. We want to be here for you. You can rely on us, Hitoshi.≈

Shouta wonders, as the young siren looks at him in bafflement and awkwardly rubs an arm, if nobody has ever said such a thing to him before. There’s a bare hint of coral-like glowing on his cheeks—likely unnoticeable to someone who didn’t know to look for it—and he opens and closes his mouth subtly a few times, lacking a response.

≈Just to be clear,≈ Shouta starts again. ≈The offer isn’t intended to make you uncomfortable or to suggest we should take the place of your pod back home—≈

≈I don’t have one,≈ Hitoshi blurts out suddenly, then immediately looks as if he regrets that.

Ah. Hmm.

Now Shouta’s the one struggling for a comeback. He’s angry, not at the youth in front of him but at the implication that the deep-sea dwellers have failed to support one their own yet again. This time, what for? Because one of his parents wasn’t trench-born? Even they had left him unbound, podless.

No wonder Hitoshi’s affection for the human kid had developed so fast, if attention and kindness had been in such short supply before.

Before Shouta can formulate a sensitive reply, the siren speaks up again, expression guarded. ≈Is… Denki part of your pod?≈

He huffs in amusement. ≈Guppy, I doubt he even knows what a pod is. Most walkers don’t understand much about merfolk.≈

Hitoshi ponders that for a moment. ≈But you look out for him. You protected him when—when I—when he was hurt.≈ The grimace prefacing his wording change is a subtle kind of alarming; if the young siren’s already feeling the instinctual, sharp mental pressures to safeguard loved ones, then he’s fallen even harder than Shouta thought.

≈I do, and I did,≈ he agrees. ≈As I explained before, when the walkers are harmed, it causes problems.≈ And if there’s more to it than that, like maybe that the kid really is growing on him (much to Shouta’s resignation and Hizashi’s glee), then he’s certainly not going to admit it out loud. Besides, he has a feeling he knows where this line of questioning is going, and puts on his sire mind again for a moment. ≈What is it you’re expecting from your relationship with him, Hitoshi?≈

The siren’s fins flatten defensively, nervously. ≈Why do you care, if he’s not in your—≈

≈Relax,≈ he interrupts, not wanting to deal with unnecessary posturing. Already Shouta can feel his throat ache as he represses a calming trill. ≈It doesn’t make a difference to me. However. ≈ He glances back at the door briefly. ≈I’m more experienced when it comes to walkers. Your friendship with him is risky, but not impossible to maintain. And yet I believe you’re starting to wonder if he could be more than that.≈

Hitoshi stays quiet and motionless, which is confirmation enough.

≈I’m not here to judge, little fish, but I’ll lay some facts out for you. Your friend can’t swim, can barely float. His legs aren’t going to heal like your injuries did. Not ever. He’ll be land-bound, and even if you learn to use your lungs, you’ll never stray far from the shore as you are now.≈ He pauses, watching the melancholy steal over Hitoshi’s gaze as the siren glances away. ≈He’s a great kid. Surprisingly so, the rare kind that are few and far between. But great enough to give up the ocean for?≈

Hitoshi’s eyes snap back to him. ≈Give it up? For… good?≈

≈It’s a trade-off. Can’t have it both ways, guppy. When you give up your fins to live on land, you’re cutting ties with the sea. You’ll lose most of your magic. There won’t be enough to turn back if you change your mind. So, decide if the kid is worth that.≈

Shouta averts his gaze. It’s painful to watch Hitoshi drift to the tank floor so quietly, eyes rounded with shock. Shit, he’s such a young thing, and he’s got enough to worry about without having to consider finding a mate. Maybe Shouta should have worded that differently, should have insisted that he didn’t have to decide now. But with the speed those two are going, perhaps this is for the best.  

He’s beginning to think their conversation has ended, when Hitoshi asks something Shouta probably should have expected at this point, all things considered.

≈ Sosvii Aizawa …  was Yamada worth it, for you?≈

When he closes his eyes, he hears the wordless whispering of magic, dim and soft, a reminder of what he gave up. With the ley-line growing stronger his memories have become clearer, and sometimes it even feels like his Song might work again, dare he use it. But he doesn’t. He knows the whispers are just echoes.

Shouta turns back to the younger siren, one hand sliding behind his neck to rub at the prominent C7 bump where a thoracic fin once began. ≈He was. Still is; I don’t regret my choice. But the sea calls and calls, and never stops, Hitoshi. And without its magic… it’s difficult to protect what’s important.≈

Behind him, he hears Hizashi open the door, and in the reflection of the tank he sees his husband— his mate, his most precious, his to take care of— step back in, followed by an anxious Kaminari.

≈So,≈ he murmurs, as quiet as he can manage. ≈Do you think you could give that up to be with him?≈

Hitoshi stares past, silent as a grave, looking utterly lost.

It’s not that Denki has anything against Professor Yamada—not in the slightest—but seeing him standing outside the tank room’s door, clearly waiting to talk, sours his already-finicky mental state.

“Kaminari! You’re back.” The loud statement strikes him as a bit odd; it’s not like there’s anyone else around to announce it to. Yamada leans down a fraction and lowers his voice. “How ya doing, kiddo?”

Gods, what a question. Over the last half-hour he’s faced emotional whiplash of the worst kind. The moment he left the tank, his dopamine ran dry as he realized that this was it.

The pit in his stomach is growing by the minute. “Bakugou says I shouldn’t have gotten attached. I didn’t mean to, but I…” It hurts, and it’s going to get even worse. But his worry isn’t for him. “Professor Yamada… if Hitoshi can’t go home, what’s he going to do? C-can sirens survive on their own?  He’s going to be lonely.”

Denki knows a thing or two about loneliness, but he’s not exiled and one of the last of his kind.

Yamada gives him a sad look. “You don’t seem very confident that he’ll come back, kiddo.”

“I just don’t see why he would. I’m… me.” He can feel himself tip-toeing to the edge of hopelessness. “I-I’ve had fun. Really, these last few days have been surreal, and I don’t think anything will ever compare. S-so… I should just be grateful that I got this much.” Denki looks at the door. “Does he know he’s going free?”

Yamada nods and steps inside.

The tightness in Denki’s throat threatens to choke him. He ducks his head and pushes through the door after the researcher, then takes a deep, shaky breath, finally ambling over to where Hitoshi waits.

“Hey buddy,” he murmurs, willing his voice to steady. “Bet you’re looking f-forward to stretching your fins, huh? A-and no more privacy invasions at all hours of the day. You haven’t gotten too attached to my five-star food service, have you?”

The absent, destroyed look in the siren’s gaze as it falls on him nearly breaks Denki to pieces right then and there. It affirms his fears, doesn’t it? His chest clenches painfully.

When the tears start falling he tries to wipe them away. “Sorry, s-sorry… y-you’re hella strong. You’ll be fine.” He hiccups, forcing a smile despite his voice breaking. “I will be too, just... y’know. I’m gonna miss our little chats.” He gives a hysteric half-laugh.

Hitoshi’s face turns concerned, and Denki can’t blame him. The language barrier has never felt so insurmountable as it does this very moment.

He’d seen Aizawa standing near when he’d approached the tank, but it still makes Denki jump in surprise when the man starts talking softly. “Your veterinarian and technician friends are on their way. Once they arrive, we need to move fast, and get him off the ship before security personally looks into why we’re opening the docking pool so late.”

The words themselves may be clinical, unfeeling, but Denki understands the meaning behind them: Say your goodbyes now. As if to punctuate it, Aizawa squeezes his shoulder and gives them privacy.

Denki’s throat tightens further—no , stop, he still has so much to say! He doesn’t want them to part with this misery having stolen his last words. As he struggles to catch a breath, he sees Hitoshi rest his head and palms on the glass, eyes closed. Denki’s tears spill ceaselessly as he mirrors it, still fighting to keep a smile that feels like it’s fracturing.

“A-am I allowed to ask something selfish? It’s okay because you don’t understand me, right?” he whispers hoarsely against the glass. He inhales deeply again. “It’s just… I don’t want this to be it. You make me feel like I’m a part of something special. Not just a shadow anymore, y’know? Maybe it’s hopeless, to want this to continue. I know the end result will never change and we’ll be left twiddling our thumbs in a tidepool, wishing for more. But that’s okay, isn’t it? I… I can’t let go yet, Hitoshi.” He releases a shuddery sigh. “So… please come back.”

The door opens. He hears Bakugou call out that Uraraka is keeping an eye on the halls – and that they need to get moving.

Everything starts to blur together into a distant mess of sounds and movements, and maybe Denki should be concerned about that, but instead all he feels is his heart sinking down, down, down. He thinks he’s stopped crying at least, loosely aware of the uneasy glance Bakugou shoots him as the other mechanic takes the stairs three at a time with a tarp bundled under one arm.

The tank is cool against Denki’s temple. He watches Bakugou and Aizawa lay the tarp at the top of the stairs, talking and gesturing to the hand-holds and to each other. Aizawa turns and says something towards the tank, then again a bit louder.

On the other side of the glass, Hitoshi looks up at the man, hesitating, then back to Denki.

“Kaminari,” Aizawa calls, his voice a warning.

Right. Right. Denki takes a deep breath and pushes away from the tank. He backs up and rubs at his wet cheeks. “G-go on,” he croaks to Hitoshi, motioning blindly up to where they wait for him. The siren doesn’t immediately move. “Go on. ” His gesture is more frantic this time.

And finally Hitoshi goes. There’s a rush of purple as he ducks low to the bottom, then surges towards the wall where he’d pulled himself up the day before. It’s more forceful this time. It has to be. He emerges with a rush of water, heaving his upper body and a solid portion of his tail over the edge, where he hits the tarp with a wet slap and a hiss of discomfort.

Aizawa gets Hitoshi’s arms around his neck while both the siren and Bakugou work to maneuver the bulk of his tail and fins onto the tarp. Yamada joins them then to wrangle the bundle down the stairs, leaving Denki to wring his hands and—and what?

“The door, kid,” Aizawa grunts, any patience in his voice diffused by the dig of Hitoshi’s claws into the back of his shirt.

Denki nods and hobbles ahead of them, holding the door open. He wants to reach out to Hitoshi as Aizawa passes by, but his limbs feel like they’ve been filled with lead. The next thing he knows he’s following their little secretive parade down the hall and into the docking pool room, where the siren had been first dragged up from the deep.

The panel blares insistently when Bakugou flips the switch to open the pool gate, and the machines underfoot groan into action.

There’s a brief pause in the action once Hitoshi is laid back down; Bakugou answers the phone by the pool’s access panel, shouting at security to say he’s looking into a reported issue, dipshit , and then don’t fucking send someone, they’ll just get in my way . 

Yamada waves Denki over. 

He obliges, stumbling to the beached siren’s side with legs even shakier than usual.

Hitoshi reaches out, upper half propped up on one scaled elbow, and snags a hand in Denki’s shirt. He’s saying something but outside the water his language isn’t as fluid, as clear. Worse yet, he’s paling quickly with the lack of water to his gills.

Denki’s struggling to lower himself when suddenly Hitoshi pulls him sharply off-balance. The flash of panic vanishes when he’s caught carefully against the siren’s chest, cradled sideways, feeling the other’s rapid heartbeat through the cold, damp skin. Aizawa mutters something but Denki can’t hear it over the deep, gentle warbling from the being beneath him.

It starts his tears all over again, and try as he might to find words, they don’t come.

Too soon, the gate clanks fully open. Hitoshi’s gaze is an inch away, somehow sharp and soft simultaneously. Denki finds himself carefully rolled onto his back; Hitoshi’s forehead meets his for one timeless moment before pulling away.

Please come back.

The siren’s form slides gracefully out of view. Then, with a splash, he’s gone.

Denki doesn’t know which of the others eases him up to sit. He hears sniffling—Yamada? Maybe. Not important.

But it’s Aizawa who sighs, “I’m sorry, kid.”

And they both hold him as he breaks.

Chapter Text

Despite attending the mess hall for lunch for the first time in three days, it’s like Denki never left. In fact, more than one person appears surprised when he apologizes for the absence. He’s pretty sure they never noticed he was gone. When he excuses himself from the table with a shaky voice and unconvincing smile, he’s unexpectedly steered by Bakugou—who never shows up for mealtime—to an out-of-the-way table. They eat together mostly in silence, but Denki’s just fine with that.

When the time comes to go back to work, the other blonde side-eyes him and grunts, “Don’t even think about it. We’re taking the afternoon off.”

“W-what?”

“You think I didn’t notice how distracted you were this morning? Fuck, Creaky, you started blubbering up at the sight of the anti-vapor spray.”

Denki lowers his gaze to his lap. Yeah, that had been pretty bad. “Sorry.”

Bakugou scoffs. “It’s – it’s whatever. But I can’t work when I gotta keep an eye on you so you don’t shock yourself stupid or something, idiot.” Then before Denki can get out another apology, he continues: “You got a T.V. in your room, yeah? One that’s not shit?”

It’s impressive in itself that Bakugou’s trying to make reasonably friendly conversation at all, so Denki is caught off guard—again. “Yes,” he answers lamely.

“Good. I’m bringing over my Switch, we’re gonna play Smash.”

The afternoon ends up not being at all what Denki expected; it’s actually pretty great. Bakugou’s a hypercompetitive beast but his running snarky commentary against both Denki and the AI is worth its comedic weight in gold. When they team up to take on two of his friends online, the guy commends him for being a good distraction for their enemies, and Denki’s certain that he should consider that top-tier praise. Maybe he could engrave it in steel and hang it on his wall.

In the evening, Bakugou fires off a few texts – and shortly thereafter Uraraka is at the door with three dinners in one hand and a USB full of movies in the other. They agree on a Ghibli marathon (well, Bakugou doesn’t, but he stops grumbling when Uraraka levels him a Look) and by the time they’ve made it through Nausicaa and Howl’s Moving Castle, they’re little more than a pile of limbs and pillows and crumbs strewn haphazardly on Denki’s bed. At some point Bakugou had pulled a small bottle of rum from who-knows-where, which it turns out has the surprising effect of mellowing him significantly.

As Uraraka scrolls through the list of movies to choose from next, Denki spots one title that makes his heart catch in his throat. Without further consideration he blurts out, “Ponyo.”

Uraraka squints at him. “Um… are you sure, Kami?”

No, he should say. Don’t listen to me, don’t play it, it’s a terrible idea. But his masochistic streak takes the reins and murmurs, “Yeah! It’s just a movie, it’s fine.”

She gives him a doubtful look. “Well… I don’t know. Wouldn’t it be a little too—”

“Just put it on, Cheeks,” Bakugou says. “He’s gonna have miserable little bitch moments anyways, might as well let them be when we’re here to help set him straight.”

That’s… astoundingly thoughtful, in the other man’s awkward, aggressive way. Denki stares blankly at his coworker—friend?—for a long moment, before grabbing the rum bottle and taking a swig himself.

“Oi!”

“Thanks, man.” Denki pushes the bottle back at him and leans against the pillows with a sigh. “You heard him Uraraka. Let’s put it on.”

She puts it on.

He’s not fine. In fact, he’s an exceptionally miserable little bitch through the whole second half, chest aching and face red from tears as he puts himself in Sosuke’s shoes. Why couldn’t he and Hitoshi find a way to make it work? Why couldn’t they have a happy ever after?

Bakugou shoves a pillow at him and throws an arm loosely over his shoulders at some point, and soon Uraraka is curled up at his side. She’s too small, and he’s too warm, but he appreciates the gesture nonetheless.

Four days after the guppy’s release, Shouta finds himself on the ship’s deck for the first time in… he doesn’t know how long, to be honest. Staring out across the seemingly-endless vista of blue hasn’t brought him peace in years. Now’s no different.

He fights the desire to throw himself over the side of the ship and dive deep, past the reaches of the sun’s light and warmth. Entering the tank had been bad enough. If he were to touch the sea in its infinity, he’d be a goner, fins or not. He doesn’t want that; if he could just live alongside the water without the primal need to return to it, he and Hizashi could breathe easier at night. Especially at a time like this.

But the fickle magic still inside him itches, burns, more demanding than it has been in decades. So he loosens his grip on the railing and backs away to a nearby bench.

Hizashi joins him not soon after, taking a seat and slipping a hand into his. “Why are we meeting up here, Shou?”

Shouta tosses words around in his brain before answering, hoping to find the least alarming way to share the news. “I overheard some rumblings from the Applied Magic division this morning. They’re picking up small surges of power in the northern region. At the barrier’s edge, but they don’t know that.”

“The barrier?” Hizashi frowns. “Does that mean…?”

“He’s found the old settlement’s protected zone, yes. Been coming and going at his leisure by the sounds of it.” He huffs a sigh. “Wish he wouldn’t be so obvious. Someone’s going to think to watch that area soon.”

Hizashi’s staring at him, mouth agape. “Hold on. You’re telling me Hitoshi stuck around and hasn’t tried to get in contact?” There’s disappointment, maybe even hurt, growing in his gaze. “I was… so sure that they were meant to be together.”

Shouta shuffles in his seat. “I may have given him a bit to think over.”

The gaze on him turns hard; he can feel its sting, can even feel some of his husband’s vexed disbelief in his own mind. “Meaning what ...?”

“He wants to protect the ley-line. I explained the difficulties that a relationship with a human would bring to that.”

“Shouta!”

“He needed to know to make an informed decision—”

“—should’ve let them work it out—”

“—and I didn’t want him to throw his dreams, his goals, everything, away for what could just be a fleeting crush , Hizashi!”

The prolonged silence that follows lets Shouta know he fucked that wording up.

Hizashi’s lips purse. “Throwing away everything, huh?” His words are breathy and soft, all wrong. The mental connection between them floods with hurt and guilt.

“You know full well I’m not referring to us, ‘Zashi,” It’s not the first time the discussion’s come up in the past century. But ever since accidentally letting slip one night long ago that he himself hadn’t known the consequences of his choice before making it, the topic has been rough.

Hizashi’s expression remains pinched.

Shouta sighs; he supposes that this whole issue has brought the uncertainty back tenfold. Squeezing his husband’s hand, he murmurs, “I still don’t regret my decisions. I told Hitoshi that, too. But Hizashi… if he made the sacrifice and then changed his mind, or something went wrong… and I hadn’t said a word…”

Hizashi wilts at his side. “Okay. I can understand where you’re coming from.”

They’re silent again, listening to the waves and the gulls and the low thrum of machinery. It’s still not very peaceful to Shouta, but with his mate at his side, it’s easier to relax.

It takes Denki nearly a week to find some semblance of routine again, but when he does, he throws himself into it. He can’t keep stressing and wondering, it’s not healthy.

Yamada makes time to track him down at least once a day. They talk about little, pointless things, never mentioning him. Denki doesn’t know if that’s better or worse. He’s only seen Aizawa once since that night, and although the man had looked ready to ask a question, he’d stayed quiet. Simply… nodded. And that was it.

At the end of the week, just when he’s ready to stop hoping for some kind of miracle, a request comes through the technician task queue that makes his blood run cold.

Salvage Footage

Rover attacked near northern ridge of plateau - operator believes creature caught on video feed prior to exterior damage - reports vivid plum-colored scales and fins that do not match known mundane sea life nor magical fauna native to this area - please attempt to salvage and/or copy the video footage for further investigation - discretion requested.

Well, fuck that.

He’s got his phone out in shaky hands before even bothering to check the rest of the queue.

Denki looks over at the rover. Its front end is battered quite impressively considering that the machines are built to be solid enough to withstand mid-sea pressure. The small attachments usually fastened to the sides are all either missing or mangled; it’s an expensive loss. The camera itself is shattered, but the memory for it should be secure, deeper in.

His phone buzzes; a call, rather than a text. He swallows before answering. “Hel—”

“How do you know that?” It’s Aizawa, more alert than Denki’s ever heard him.

“A request came through my queue. It’s— it’s him, I know it, even if it’s vague—”

“Read it to me, Kaminari.”

He does, voice a bit shaky, but the man on the other end doesn’t comment on that. In fact, he’s quiet altogether for a long pause after Denki’s done.

“Who made the request?”

Denki skims the message. It’s a name he doesn’t recognize. “U-uhh, some guy called Okuta Kagero?”

Aizawa swears under his breath. “Kid, destroy the video. Use whatever you think will work. I have some things to take care of on my end. If the workshop has a drone available, get it ready. I’ll get in touch again shortly.” And then he hangs up.

Denki’s never been good at magic tricks or misdirection, but when it comes to destroying electronics beyond even his own repair, he’s a pro. Maybe he shouldn’t be so eager to zap the memory chip until it’s fried, but chances to play with electrical currents are few and far between, and this is for the best cause he can possibly imagine. One short-circuit later, he’s confident that the recording is gone for good.

It’s then he notices a message from a few minutes past:

Aizawa doesn’t look at all comfortable. The man’s casting side-glances at the water as if he expects it to rise up and grab him any moment, while simultaneously fiddling with what appear to be several knotted strings attached to a loop. Beside him, Yamada holds a stone with a hole bored through it. He at least looks happier.

“Hey. What’s the plan? How can we throw them off?” Denki asks, setting aside his cane to fetch the drone out of the box. “Just so you know—this isn’t waterproof.”

“It doesn’t need to be. It’s just a delivery vehicle,” Aizawa grumbles. “For this.”

The collection of strings is… unimpressive, honestly. If Denki didn’t know the man better, he might guess that it’s just a frayed net, discarded and thrown away. Each string is knotted at different spots along its length, some more intricately than others, and a few have what seem to be fragments of shell and beads tied into it as well.

Before he can ask, Yamada leans in, stroking along one of the strings reverently. “A mer message,” he says with a smile.

“A warning.” Aizawa’s fingers deftly tie another bump in the last string. Then he takes the stone from Yamada and feeds the master loop through it, tying that off as well. “Hitoshi will likely be more cautious now that he’s been spotted, but that’s not enough. Destroyed footage won’t prevent follow-up.”

Denki swallows. “You think they’re going to hunt for him?” Like an animal. He gets the mental image of harpoons and nets, Hitoshi’s snarls and fear, and very nearly loses his breakfast. “They—they wouldn’t hurt him—couldn’t—could they? There’ve been treaties and laws in place, for like—”

“One hundred and seven years,” Aizawa answers automatically, voice low.

Yamada settles a hand on his husband’s back.

Once handed the strange rock-and-string creation—(a message?? He has so many questions)—Denki secures it to the graspers of the drone. “So we just drop this and wait for him to find it? How do we even know he’s in the right area?”

“It’s an estimate. We’ll lure him to it.” He pulls out a switchblade, then hesitates, and hands it to Yamada. “My blood…” he says, then clears his throat. “…he won’t recognize it.”

Of the three of them, was Aizawa really the only one who hadn’t been bitten or sliced? Denki’s own injury had been obvious and quite the cause for panic, and he distantly recalls the scrapes on Yamada (and everyone else in the water, for that matter) from wrangling Hitoshi into the tank the first day.

Yamada takes the knife with a grimace, looking nauseous.

“Use mine,” Denki says, before he can regret it. “I get cut up at work all the time anyways, it’s nothing. Plus he’ll definitely recognize mine, yeah?”

There are no protests. A minute later, the strings are splattered with red and Denki’s holding a cloth to his elbow to stop the bleeding. He watches Yamada inexpertly navigate the drone with its package far to the north, until the controller beeps a distance warning some three miles off. The ‘message’ is released to sink deep into the ocean below.

“And now we can only hope he gets it,” Yamada sighs, reversing the machine’s course until they’re able to retrieve it at last.

It feels too… simple. Not enough, just as Aizawa had said earlier. The thought of sitting around on this ship tinkering while Hitoshi might be putting his life at risk nearby is—

“Hold on,” Denki says slowly. “Why is he still this close? I know he can’t go home but the plateau is so shallow, there’s nowhere for him to hide!” A note of anxiety creeps into his voice unprompted. “What did that knot warning mean? We need to be specific—”

“ Kid. Calm down. There’s nothing we can do at this point except wait.”

Yamada sighs. “He’s worried, Shou.” A pause. “Kaminari, you mentioned the laws that protect mythical beings earlier. Do you know what event made them come about?”

He wracks his brain, but those high school history classes were too long ago. He shakes his head.

“Hizashi…” Aizawa grumbles.

“Love, I’m putting my foot down for this. You helped out your parallel protégé.” Yamada clamps a hand down on Denki’s shoulder and steers him towards the door. “And it’s high time I did the same for mine!”

Protégé? Denki thinks weakly as he’s escorted down through the ship to the bunk cabins. Yamada is a constant source of chatter the whole way, explaining the history of the old merfolk settlement of the Ogasawara Plateau. Its residents weren’t sirens like Hitoshi, but another subtype of mer known as ‘coral-fins’—smaller, brighter, and far less aggressive than their trench-dwelling kin.

“Hitoshi didn’t seem too aggressive,” he murmurs as Yamada fiddles with the door.

“No,” Yamada agrees. “But there are reasons for that. Come on in.”

It feels like stepping into a curiosities shop. For a three-month expedition, the pair have gone all-out, lining the walls of the common area with countless shelves. Each is filled with baubles and oddities of all sorts – jars of sea-glass, pottery both cracked and pristine, carved idols, semi-precious gemstones in heaps, stunning shells, and plenty of suspended string-messages like the one they’d dropped into the sea. Interspersed between the displays are various books and what appear to be hand-written journals.

Whistling, he turns in place. The collection really is impressive. “Nice treasure hoard,” he jokes.

“…Thank you,” Aizawa responds, to his surprise. The dark-haired man walks past and disappears into an adjoining room wearing an expression halfway between irritation and sheepishness.

Yamada steers Denki down onto one of the couches before plucking a pair of textbooks off a nearby shelf. “Don’t mind him. He’s not good with certain discussion topics, no matter how much they need to be addressed. But we can’t keep skirting around your involvement, can we?”

The upturn in volume at the end of the question leads Denki to believe that it’s not just meant for him. “Uhh… no?”

“No indeed. Unless you’ve changed your mind about protecting Hitoshi at all costs.” Yamada’s pale green gaze spears him to the couch. “But I don’t believe that’s the case.”

Denki’s breath leaves him in a rush. “I’ll do anything. ”

The professor’s intensity washes away like a tide over sand, leaving behind a wide grin. “I knew I recognized a kindred spirit in ya, Kaminari! You remind me so much of myself once upon a time. Speaking of…” he slides one book over, and his voice turns serious again. “The event I alluded to, the one that heralded the laws. Hits close to home, wouldn’t you say?”

The title before him reads ‘Genocide at Ogasawara: pre-treaty extermination of merfolk for magic’.

Denki rereads it three times before the reality of the title hits him like a punch to the gut. “Here? This settlement is what brought about the protection acts?”

After weeks of working in close conjunction with historians and researchers, he’d picked up on some of the old beliefs surrounding the mer, ideas formed when anything non-human was feared, envied, and treated like a beast. Among those was the nauseating theory that consuming mythical creature parts grants power—long since disproved—and that magical beings guard ley-lines to gatekeep humans from deserved ascension.

It’s no secret that Ogasawara Plateau once boasted one of the strongest ley-line paths in the Pacific—that was a fundamental interest of the expedition, after all—but it had never occurred to Denki that it might have brought about the disappearance of the local mer.

No—not disappearance. Slaughter.

Hizashi slides a bowl of ginger candies across the table to him. “The mer themselves are protected these days, as you pointed out. The laws defend magic-inherent populations globally, and was a brilliant step forward for relations between the mythical and mundane. But it can’t rewind the bloodshed on the plateau, and it specifically doesn’t protect that which the mer hold dearest. What they’re compelled to defend.”

Denki leans back, head swimming. “The ley-line. But—this one’s dead, I thought.”

“Not dead, Kaminari. Dormant. For over a century, certainly, but various sources believe that something big is about to come from it very soon.” Those green eyes glimmer.

Denki may not be a genius, but he can connect the dots just fine. “That’s why Hitoshi stuck around? He’s drawn to the ley-line waking up.” It makes more sense than staying for Denki’s sake, especially considering the siren hasn’t come to visit.

“Magic calls to magic,” Yamada says. “Shouta and I think he’s found the heart—that is, the chamber that gives shape and life to Chaos. He felt it pulsing earlier than the rest of us. But once the ley-line wakes up entirely, others—non-mer—will clue in. He’ll fight them to keep it safe, if he has to. That primal compulsion runs deep.”

Goosebumps crawls over Denki’s arms. “Fight them alone?”

“Not if we can help it,” Aizawa murmurs from the doorway, arms crossed.

Looking between the two of them, Denki can’t help but feel like he’s being tested. Yamada’s leaning towards him, bright and encouraging, a due contrast to the doubtful and guarded posture of his husband only paces away. There’s a kind of untouchable static that hangs in the room, eager to snap, building pressure. But towards what?

His mind turns to Hitoshi; dangerous, beautiful, fascinating, powerful Hitoshi. The thought of him hurts like an open wound, inexplicably raw despite the short time they’d spent together. It doesn’t make sense; none of the others seem as affected, as displaced from who they were before. It’s as if Denki’s life has been split into two defining halves, neatly bisected from the moment Hitoshi had said his name. A paradigm shift that’s left him floundering, lost, with only one light to guide his way.

“Please.” Denki swallows thickly, turning so he can face the two of them, folding his hands in his lap and dipping his upper body respectfully, desperately. “I know I’m just a kid to you. I don’t even know what use I can be. A-and maybe it’s weird that I feel so strongly about this, but I do, like I’m being compelled.” Heat burns in his eyes. “So please let me help. Let me fight with him, for him, however I can!”

He’s swept into Yamada’s hug at the first shuddery sob, and just lets it happen, giving into an encore of the pain from a week prior. This time, at least, he’s able to stay grounded, listening.

“Notoriously stubborn heart-thieves, aren’t they?” Yamada says softly. “I knew it was more than a crush. Your pain looked too familiar.”

Denki glances up, confused.

But his question is interrupted by Aizawa kneeling down beside them. The scruffy man’s eyebrows are tight and low, the line of his lips apologetic. “It seems I made an error in judgment. I wouldn’t take back my cautions to Hitoshi even if I could—they’re still important, regardless—but I am sorry for doubting you, Kaminari.”

Yamada continues. “I’m sure when his goals have been met, when there are others to help protect the ley-line, he’ll leave the sea for you if you ask. Until then, of course you can help—”

“Hold on, no,” Denki interrupts, pushing back from the man and swiping an arm over his own eyes. “What? Leave the sea?”

The ticking of the wall-clock fills the brief silence before Aizawa murmurs, “If he chooses to give up his magic, Hitoshi can live with you on land. Functionally, that is. Like a human.”

At first, Denki thinks of Ponyo , and the miserable prayer he’d made curled around a pillow with his friends bracketing either side. This was the chance he’d asked for, wasn’t it? Some small miracle to make it all work out.

But that was before he’d learned about the imminent magical surge and Hitoshi’s determination to safeguard the ley-line once and for all. A renewed purpose, following the near-eradication of his people. A goal which would no doubt require every bit of magic the siren could muster.

“I would never ask him to do that. I don’t want to make him choose.” He steels his shoulders, meeting Aizawa’s gaze. “We’ll make it work some other way. As long as I know he’s coming back to me… I can be happy.”

Aizawa, in a rare wide-eyed display, merely blinks.

Denki finds himself tugged unceremoniously back into a hug by the more emotive of the pair, Yamada blubbering something that sounds remarkably like ‘can we keep him, Shou?’ , along with scatterings of praise and other reassurances. He laughs and pats the tall man’s back awkwardly.

“Really, it’s— it doesn’t take much.” He looks at his hands. “My stuff on the mainland’s in storage. Nobody’s waiting for me back there. Chichijima could probably use another mechanic, right? And then when I’ve saved up enough, I’ll buy a boat to live on the water as much as I can.” He’d been writing ideas of the sort in the margins of his workbook all week, figuring out the logistics of a dream. But... there was one hang-up. Denki frowns. “The language barrier is the kicker. I dunno know how to approach that.”

Yamada chuckles, and lets him go with a sly glance at his husband. “I think we can help in that regard. Shouta’s something of a natural.”

Said husband looks thoroughly unamused. “Spell it right out for him, why don’t you?”

“Come on, love, he’s going to learn sooner or later!”

“Then let it be later.”

Denki stares at him. “You know how to speak their language?”

“Oh yes, rather fluently,” Yamada says, suddenly far too jolly. “We’ve had quite some time to teach each other, little listener. You see, he and I were also hopelessly smitten and facing that same barrier, once!”

“Hizashi!”

“It’s technically later, dear.”

Denki tunes out their bickering in favor of letting the puzzle pieces come together. They do so awkwardly and with great difficulty, like a toddler mashing a square block into a circular hole until it somehow defies logic and physics to pass through. And pass it does, because he’s suddenly picturing Aizawa with horns, fins, and a tail, and it… isn’t completely unbelievable.

Actually, as the seconds pass by, it starts to make sense. A small part of him thinks that maybe he should be more surprised by this revelation, and yet that part is dwarfed by relief and—dare he say hope?

“Okay… alright. I have… so many questions,” Denki mumbles, catching both sets of eyes. “But for now, just… does Hitoshi know?”

Aizawa, caught in a smothering and seemingly pacifying hug from behind by his toothpick of a partner, just sighs and nods.

Denki huffs out a laugh, eyes wet. “That’s—that’s great. Shit, man. He’s not alone.”

Once again, the man appears taken aback. “Pardon?”

“I said he’s not alone. ” He chokes back his tears; at least they’re happy ones this time. “I kept thinking how sad it would be to have nobody to talk to—let alone relate to. But he has you!” A strike of realization hits him, and he laughs again, leaning back as if allowing relief to flood through his whole being. “So you’ve already chatted with him then, yeah? Kinda jealous, not gonna lie. What’s he like, really?”

There’s a strange roughness to Aizawa’s voice as the man retorts, “He’s a brat.”

Denki’s grin is borderline painful. “Sounds about right.”

“Shouta’s attached,” Yamada supplies gleefully.

The other man doesn’t try to deny it, merely rolling his eyes before speaking again. “That aside, the issue of contacting him still stands. I’m confident he’ll find the warning, but he still can’t approach the expedition ship safely. One-sided feedback won’t be enough.”

The giddy high comes to an abrupt, sobering close. Right, there’s still the matter of actually helping the siren. Words wouldn’t ward off greed.

“That house-boat I’m gonna save for would be great right about now, huh,” Denki mumbles. “Don’t suppose one of you has one laying around?”

Aizawa shakes his head.

His husband, however, taps his chin. “ We don’t… but…” He twists his lips thoughtfully, giving Aizawa a side-eye stare. “Shou… she can help.”

The dark haired man’s puzzlement lasts a solid five seconds, before his brows slam down close over a sharp glare, a muscle in his cheek twitching. “No. Absolutely not.”

“She’s your friend! I know it’s been a while, but she did offer a favor...”

“‘Zashi, last time she also tried to eat you.”

Yamada waves a hand flippantly. “It’s been what, half a century? Forgive and forget! Besides, what other options do we have?”

It’s almost possible to see the gears clicking and whirring in Aizawa’s head, searching for any possible positive answer to that question. Denki stays silent, wondering whether he should take that last exchange with a grain of salt or be thoroughly worried.

By the way the ex-siren’s shoulders droop, he’s got a feeling it’s the latter.

“I don’t like it,” he growls. “But you’re right. Give me the phone.”

Chapter Text

The ominous words about Aizawa’s ‘friend’ tumble about in Denki’s brain, growing wild and nightmarish in his imagination as a middling yacht drifts closer to the Shinkai Maru. It’s painted dark like the evening sky, with ‘Midnight Lady’ printed in script along the side, and surprisingly quiet for a boat of its size. The sun’s been down for hours already, leaving the smaller watercraft lit only by its surroundings and a few vividly-colored lanterns onboard. Denki’s pretty sure those aren’t regulation, but can’t imagine pointing that out to the woman giving them a shark-like smile from the deck.

“Don’t touch anything that isn’t explicitly offered, don’t bother making conversation with her crew, don’t stare too long at or into any gemstones, and definitely do not make any deals with her unless one of us is there to hear and review it,” Aizawa mutters under his breath at Denki’s side. “Preferably myself, as Hizashi isn’t so great at following those rules either.”

Yamada barks out a laugh that’s only slightly offended. “I thought it was just a harmless game!”

Aizawa shakes his head and starts towards the connecting bridge, muttering “Humans,” with quiet exasperation.

With a deep breath, Denki follows.

The woman is tall, with layers of blue-black hair like an oil slick and a dress that could have been painted on for how little it hides. As they approach, Denki realizes that what he’d initially believed to be a cocktail mask or elaborate make-up… isn’t. The darkness around her eyes, cheekbones, and temples is the result of sparkling dark scales in a similar shade to her hair. And now that he’s paying attention, the tops of her arms all the way down to her knuckles are speckled with them too – passable as tattoos, if he didn’t know better.

And gosh, she’s beautiful. With the way she’s holding herself, full to the brim with distilled confidence and swagger, she knows it.

“Nemuri,” Aizawa grunts when they’re all only paces apart.

The woman—Nemuri, he supposes—isn’t deterred in the slightest by his lack of enthusiasm. If anything, her grin only widens. “You look like death warmed over—” She says what must be the Mermish pronunciation of Aizawa’s first name, if his grimace and the sounds are to go by. “…Oh, but you go by something else now too, don’t you? What was it… Asaya? Asawa?”

“Aizawa. But just use Shouta.”

Nemuri’s electric-blue gaze seems to shine. “Ah, mhm. You’ll have to forgive my memory; it’s simply been so long.”

Aizawa huffs and pushes past her onto the boat. “Not long enough.”

Next is Yamada, who puts in a good effort to match that frightening smile. “Nemuriiii! How’s my favourite sea witch doing?!” There’s something in the way he holds himself away from her that Denki immediately replicates.

She bellows a laugh that echoes over the water. “I’d say staying out of trouble, but I suppose our definitions on that differ, don’t they? Worry not, Hizashi dear. I’ve set my sights on less taken humans in the last few decades.” She waves him on, though thankfully he only moves one step past her before turning and waiting.

Because Denki sure isn’t ready to deal with whatever this lady is alone. Even without her heels she’s tall, and now she towers over him, all sharp teeth bared in a smile under needling, curious eyes.

“Well! Aren’t you a pretty little thing?” she coos, leaning into his space. “You’re not one of us, and Shouta’s stingy about expanding his pod—so what brings you onto my humble home?” Her eyes rake him up and down. “Are you a gift? I always have had a thing for blondes—”

“He’s taken, Nemuri. Leave the kid alone.”

She clucks her tongue. “Shame. I suppose you must be important. May I at least have your name?”

Denki’s mouth is cottony and dry. He doesn’t know what being a ‘gift’ would have entailed, and isn’t sure he wants to know, either. Up close, Nemuri radiates power. Her aura, for lack of a better word, is immortally hungry, ocean-cold, and dangerous, and without any of the reassurance that Denki found in Hitoshi. If she’s a siren-turned-humanlike as he suspects, she’s on a whole other level than Aizawa, who’s watching the exchange of words with sharp eyes.

“Kaminari Denki,” he croaks. His feet feel frozen in place.

“Stop dawdling and sit down, all of you,” Aizawa calls. “He’s relevant to the favor we’re calling in. You’re going to want to hear the whole story, and the sooner we can get that over with, the better.”

Nemuri gives a dismissive wave, but turns around and stalk to the lounge couches where the other ex-siren waits. The seating area is lit by a multitude of tiny, vibrant lanterns, strung from the poles that hold up a blanket canopy overhead. It’s surprisingly cozy, Denki thinks, if also unnerving. Beneath the tented canopy, mer string-messages and fascinating chains of semi-precious stones dangle from above. Their glinting and reflecting of the lanterns’ hues is mesmerising.

Yamada’s hand lands on Denki’s shoulder. He pulls his gaze away quickly, remembering the warnings.

Thankfully, he’s not the one left to explaining the situation. Aizawa recounts the events of the last week clinically, voice an even monotone all throughout. For all of her earlier excitement, Nemuri’s expression blanks then hardens as the man paraphrases his first conversation with Hitoshi in the tank—and even Denki learns a few things from that.

It’s hard to pay close attention after a quartet of guys his age or slightly older emerge from below-deck with a platter of food and a pitcher of wine. They’re human, he thinks, but something is fundamentally wrong about them; their spoken offers are polite to the point of awkwardness, but if they feel the same way, it can’t be read on their unnervingly-serene expressions. When they smile and laugh at Nemuri’s provocative jabs, it reminds Denki of bad actors with an even lousier script.

“Why Kaminari,” the sea-witch purrs, bringing him back to focus. She wears a smile like a sword. “Have you taken an interest in my Midnight Boys? They’re devilishly handsome, don’t you think?”

They’re uniformly tall and broad-shouldered, suspiciously sculpted, and each pulls off a unique, fitted outfit like he was born to wear it. Yeah, the ‘Midnight Boys’ are unquestionably attractive even from an objective standpoint. That arguably makes the whole effect even more jarring.

Denki means to agree with her, but nerves catch his tongue, and instead he blurts out “What’s wrong with them?” Shit, her stare is narrowing. Better elaborate. “They—they look like they’re bewitched.”

She sips at her wine, vivid eyes trained on him all the while, before replying with a small smile. “And if they are?”

First of all, that’s creepy as hell, he thinks but—thankfully—does not voice. Something about Nemuri tells him that she would only get a laugh out of that. Denki forces himself to shrug, scouring for a way to finish the thought. “W-well, you’re… a siren, right? Don’t merfolk lose their magic when they choose to live on land?” He looks over to Aizawa for confirmation, but the man’s half-lidded glare is focused out at the waves.

Nemuri flops back against the rear of her chair with an exaggerated sigh and pout. “Yes, yes. I haven’t had my sea magic in ages. I feel terribly empty without it, even after all this time.”

There’s a sharp laugh from Yamada. “Growing tired of humanity already? You’ve got more of the caught-between-worlds look going on than I remember.”

She smiles again, but it doesn’t reach her eyes. “Humans are fascinating and pliable, so eager to please, but I don’t want to be one. It’s bad enough to be missing my Song, let alone the rest of it.” She waggles her fingers near the tattoo-like scales on her cheekbones. “I’m not going to torture myself by staying out of the water like dear Shouta! Why would I punish myself to look so mundane?”

“Common sense for survival,” Aizawa grumps.

“Oh hush. My boys aren’t about to tell anyone my secrets.” She turns back to Denki with a conspiratory smile. “They’re not under mer magic, dear. There are alternative, wider-spread binding spells that do the trick perfectly fine.” One half-scaled hand rises to the chain of crimson glass teardrops strung beneath her collarbone. “Don’t you worry, I obtained their express consent.”

 The air hangs heavy between them for a moment, before it clicks and Denki straightens with a choked gasp. “Blood magic—but that’s illegal!”

The siren-woman cackles as if he’d just told the funniest joke, and, to Denki’s mild horror, even Yamada grins. What’s there to find amusing about the topic? Even those who don’t dabble in magic at all are taught from a young age just how taboo blood bindings are—dealing with life forces, irreversible pacts, servitude, and control—and the laws are clear. He mumbles that much.

“Aw, precious human boy,” Nemuri huffs, a grin stretched wide over razor-sharp teeth, “Your laws are narrow-minded. Selfish, even! Eager to erase practices that the longer-lived races have treasured since long before your conception.” She turns and accepts another drink from one of her human Ken dolls. “You’ll change your mind when it comes to bonding, sweetie.”

“Huh?”

“Bonding.” She swirls her drink. “With your mate? That’s how you’re involved in this, isn’t it?”

Denki’s face heats so fast he might as well have been dunked in scalding water. “We’re not mates,” he insists with a squawk, the word awkward and weighty on his tongue. Across from him, Yamada howls with laughter; even Aizawa looks vaguely amused. The term has other implications Denki doesn’t want to work out the logistics of—it feels animalistic. Is that a problematic mindset? He rubs the back of his head and chuckles weakly. “I just really care about him, like… a boyfriend! O-or something. We haven’t really talked about anything like that—or um. Talked about anything at all? So maybe I’m just assuming too much, and…”

Nemuri cuts him off with a dismissive noise. She raises an eyebrow at Aizawa. “I thought you said he was taken?”

“It’s a work in progress,” Yamada laughs. “We gotta make sure the little listeners can actually understand each other first!”

The sea witch coos, leaning into Denki’s space, a new interest in her eyes. “So, you startle at the idea of a mate, but you’ve made plans to stay with him long term. Hmmm?”

Denki opens and closes his mouth several times in succession. Yeah, he has sketched out mental plans to that degree, hasn’t he? He can’t find the words to relay it though, his brain still stuck like a scratched record on ‘mate???’

Nemuri’s cold, partially-scaled hands are suddenly cradling around his face. “Oh, isn’t that just precious? Going through all this effort for a pretty young guppy who hasn’t even made anything official. Those were the days, weren’t they, boys?” She flashes a razor-toothed grin to Aizawa and Yamada; when her lidded stare returns to Denki, it’s run through with playfulness that makes him feel small. “Take your time, dear. Auntie Nemuri is here for when you have questions!”

He resolves to never, ever go to her with questions.

She gives his cheek a fond little pat and sits back. “So! Why don’t we reel in our little fish? I’d like to meet the fin-biter who’s stirring up such drama both above and below the surface.”

The two seated men turn their faces his way; Yamada’s is unbelievably eager.

Wait. Like, now?

Denki bolts upright in his chair. “Can we?” he squawks, heart doing flips in his chest. “Do you need my blood again? Here—” he bares the same elbow they’d taken from earlier, yanking aside the bandage.

“For someone so concerned with blood magic, you sure are eager to partake in it, little one,” Nemuri chuckles. “Let’s get started, then.”

They take the boat north several miles. Denki vibrates nervously with every breached wave, until at last they come to a stop, and Aizawa brandishes a knife (vehemently denying an over-eager Nemuri the task). This time a message isn’t needed; they simply tie a bloody string through a bored stone. Aizawa mutters over it before they drop it right off the side.

Denki watches the droplets seem to glow as the stone sinks, then it’s out of sight. He stays eagerly leaned over until Yamada pulls him back with a laugh.

“It’s not going to be immediate, kiddo! Just relax.”

But he can’t imagine relaxing right now. Still, he takes a seat and tries to calm himself down, to distract from the impending reunion. “So… you went through this too?” he asks Yamada as the ex-siren pair wander to the other side of the deck to talk.

“The circumstances were different—but yes.” He pauses. “When I first stumbled across the plateau’s merfolk, I thought, ‘this must be a dream’! They were friendlier than you could imagine, especially to an aspiring musician. They pulled me into nightly songs, dozens of them surrounding my little boat in the light of the evening…”

Yamada swirls his drink, the smile written on his features bittersweet. “The coral-fins were truly a wonder. Bright, colorful, drunk on life and magic and potential. But it was the outsider living among them that caught my eye. And I, his, turns out.” His eyes slide over at his husband—mate? —and pin there with growing warmth, as if the man were Adonis instead of easily passable as a homeless transient.

“Okay, so, you don’t look half as old as what you just said implies.”

The man laughs sharply and tosses back his drink. “Mate bonds have their perks, listener,” he sing-songs with a grin.

Denki flushes again, not really wanting the mental image that pops into his head every time the word ‘mate’ is brought up so casually. “What—er. What exactly does it… mean? To be mated?” There’s a solid chance he’s going to regret asking.

Yamada reclines in his seat, resting an elbow on the side of the boat as he turns to face Denki. Amusement dances in his eyes, as if he’s actually enjoying this. He props up his cheek with a palm. “Well, ‘husband’ doesn’t mean much to the mer, you know? Shou and I have the paperwork to satisfy our human laws, but really, there’s no comparison.” His gaze loses focus, voice softening. “Mates are like nothing else. To be magically bound, hearts and minds linked… there’s no closer bond of love.”

Denki folds his arms across his midsection uneasily. The butterflies in his stomach won’t settle; he really shouldn’t have encouraged this conversation. “Hitoshi and I aren’t—I mean I don’t feel like—that.” He’s already having a hard time justifying why he thinks of Hitoshi every night without dragging the small-but-complicated ‘L’-word into things.

“No, perhaps it’s too soon. But there’s no harm in love, Kaminari. For a human to be chosen as a mate by any mythical being is an unparalleled honor.” Yamada stops to think, and idly touches the back of his neck. “There is a lesser bond, but it’s… ah.”

He motions off to the side, and the younger blonde follows his gaze. Aizawa and Nemuri have both gone quiet, alert gazes turned to the water.

“I think our invitation found its recipient,” says Yamada. His words are audibly curled by a smile.

Denki’s brain parses the words far too slowly, then he turns so quick in his seat he nearly wrenches his back. The sea is dark and calm, water gently lapping against the Midnight Lady’s side, the crests of the small waves reflecting back the pale golds, reds, and whites of the lanterns and moon.

As his gaze flits about the choppy surface, he thinks he sees movement below the water, but it’s still too dark to make anything out. He’s overcome by the sensation of being watched—his mind insists he’s here even when his eyes don’t have the proof to back it up. He struggles in his seat until his hands are braced on the rails and he’s bodily halfway over the side, aware but uncaring of Yamada’s whoop of alarm and the hand that tangles itself in the back of his shirt.

“H-Hitoshi?” He peers further into the waves. His heart is hummingbird-fast in his chest, as if it’s planning to beat itself right through his ribcage and into the sea. “Hitoshi, I—”

Two points of lilac light flicker and glow in the darkness.

That’s all it takes. The moment stretches on for an eternity, but those gleaming points—those eyes—anchor Denki’s brain to the shadows of a face, of ear-fins and horns, and an untamed sweep of hair.

His smile almost hurts. “I see you.”

And, as if someone had flipped a switch, suddenly the siren hidden beneath the waves is anything but. Markings all across Hitoshi’s body break into glow, imperfect lines and rings and spots like someone had taken vivid tyrian paint and a blindfold and then wrote a love letter, sans alphabet, across every stretch of open skin and scales.

He’s breathtaking, outshining the lanterns and stars, but most importantly he’s back.

Denki has only a moment to disregard the surprise and murmuring from the adults before his luminous siren surges up, breaching the water by half a dozen feet to grasp at the railings of the Midnight Lady—and there he hangs, sure-gripped and soft-eyed, as Denki forfeits stability to meet him halfway.

“This a new trick of yours, or are ya just that happy to see me?” he laughs wetly, dropping an arm to loop as much as he can around the back of Hitoshi’s head and neck. Both are speckled and striped with bioluminescence that dims above the water. The siren’s feathery hair soaks through his sleeve instantly, numbingly cold, but it’s proof that this is real.

Hitoshi’s half-lidded gaze and slow smile feel like a warm blanket draped around Denki’s shoulders to chase off the chill of the last week. It still doesn’t make sense, but maybe it doesn’t have to. The siren lifts himself just a few inches higher, breaching the quiet space between them, and Denki mirrors the action until their foreheads touch at last.

There’s no reasonable, scientific explanation for the way his breath comes easier, or for how his heartbeat seems to slow as if it were given an executive order from somewhere beyond Denki’s own mind. Reassurance settles into the cracks of his fractured emotional state like cement until there’s no room left for worry or doubts to sneak in. The relief is nearly tangible, and certainly mind-boggling. Last week it had been pacifying, sure, but now? It’s a high.

If this is a sort of magic—and what else can it be? —then maybe a bond isn’t such an frightening idea after all.

Hitoshi eases back, the hiss-whisper-chirping of his language rolling through the night air. The lazy grin he wears sends a bubbly feeling through Denki’s chest, but doesn’t help much with what’s lost in translation.

“He says he’s going to need your help again after all,” Yamada says from behind him. Because, right. Turns out people around here do speak Mermish.

Denki nods his head before even realizing he’s doing it. “Of course! Y-yeah! Totally. With what?”

Hitoshi murmurs something else, then one railing bar at a time lowers himself back into the water, out of Denki’s reach. Within moments of slipping fully into the sea, and without his bioluminescence to mark his spot, he’s practically invisible once again. It’s only his eyes that are clearly seen, glowing, waiting.

Denki straightens up in concern, stomach aching from where he’d been bent over the metal bars. “With what?” he repeats, turning to Yamada.

But it’s Aizawa who answers this time. “With finding an entry point,” the man says. “He’s coming aboard.”

Chapter Text

It doesn’t occur to Denki until the moment Hitoshi drags himself up over the stern that there are obvious complications with him coming aboard.

“Of course he chooses now of all times to learn,” Aizawa mutters as he brushes past where Denki stands watching, more hurried than usual. The man crouches abruptly at Hitoshi’s side, ignoring the hiss of protest as he hauls the siren by the underarms up a few extra feet until the bulk of his tail is settled safely on the boat.

Then he clamps his hands around Hitoshi’s neck.

Denki startles violently, nearly tripping over his own feet with a strangled, “ What— ” – only to be held back once again by Yamada.

Hitoshi visibly bristles, fins flared and lips pulled back, but there’s no fight to it. His tail rolls thunderously against the docked sea-doo next to him, then twists up with discomfort, even as he makes no attempts to tear Aizawa’s broad palms away from his throat. From his gills .

The man’s not pressing anywhere except right where he needs to, Denki realizes. Aizawa whispers something guttural and sharp, and it takes a moment to register as Mermish, unusual and deeper and with more breath than Denki’s used to hearing. Aizawa thumbs the side of Hitoshi’s jaw insistently. Says something else, then repeats it louder, like an order.

“The first breath is always the hardest,” Yamada explains wistfully, grip easing on the back of Denki’s shirt as the truth of the situation unfolds. “It’s not instinctive for them like it is for us, you know? Especially the deep-sea dwellers. If you think it’s uncomfortable to watch, just imagine wilfully suffocating yourself to the point of waking up organs you’ve never used before. Many mer never manage it.”

Denki makes a sound like a strangled seagull.

Yamada laughs. “Shouta’s mindful of that, don’t you worry! If Hitoshi chickens out, or worse, the water’s not far.”

“He’ll be fine,” Nemuri murmurs, further back. “He didn’t overcome everything else to be beaten by his own lungs. Have some faith, blondie.”

Still, it’s enough to make Denki shrug out of Yamada’s hold and hobble his way to Aizawa’s side. He tugs at Hitoshi’s iron grip around Aizawa’s forearms, easing his fingers under the siren’s one at a time until eventually the dusky hand slides into his own.

The siren’s eyes drift to him, pupils like pinpricks, and it’s impossible not to see the quiet alarm within them. Already, he’s losing color, the tips of his fins paling like diluted ink as his face shifts towards gray.

“Hey buddy, Hitoshi.” Denki squeezes his fingers and Hitoshi returns the action quick and hard enough that Denki’s joints creak. He bites back a wince. “Don’t wait for me to give ya mouth to mouth or something, okay? I’ll do it—but that’d be like, the least cool way for you to take your first breath, and I’ll get to lord it over you forever.” He quirks a grin, once again drawing a weaker imitation from the merman below him, even if the joke itself is lost to the void of language barriers.

Mostly, anyways. Aizawa gives Denki an exasperated sideways glance but says nothing in Japanese, returning immediately to coaching in a language Hitoshi can understand.

The ex-siren taps Hitoshi’s jaw again, more forcefully, saying something in the hiss-click of Mermish before indicating to his own nose and mouth. He opens the latter and takes a slow, deep breath. His shoulders rise and chest expands, clearly drawing Hitoshi’s bewildered gaze.

It should be fascinating to see this veteran immigrant to the human world teaching a newbie, but all Denki can think about when Hitoshi forces his muscles to contract along his chest and abdomen in a confused mimicry of an exhale is that there’s definitely no air to it. The siren seems to realize this too, wearing a grimace and a slightly hazy gaze, now fidgeting urgently. His reply is short and broken, volume not carrying without water or working lungs to boost it.

Denki swallows. “I was kidding with that CPR joke, but if—”

“He’s got it,” Aizawa interrupts.

“Right, right.”

Except not right, because Hitoshi’s eyelids flutter and fall even as he tilts his head to look at the sea just out of his reach. The hand not clasped in Denki’s scrabbles against the floor towards it, and his mouth works open and closed, teeth gnashing quietly – the next thud of his tail is devoid of strength – his whole body shakes and jerks and it’s awful to watch, he’s suffocating –

Head snapping up, Denki sees that Aizawa, too, is frightfully pale, lips pressed thin. The horror that comes with that’s enough to make him choke out a pleading, “ Sir, ” grabbing for the man’s strong forearm as Hitoshi’s grip weakens.

Then there’s a violent, desperate rasp like a breeze howling through closed shutters, and Aizawa wilts with relief and a few quiet curses.

Hitoshi’s arms swing up aimlessly for a moment, chaotically knocking both of their hands away then pressing with alarm over his own ribs. The wince on his face is threaded through with shock, the immediate exhale sharp and heavy, much like the gasping next breath that follows.

He’s breathing. He’s breathing.

Denki shakes off the wetness in his eyes, sitting back with a sigh of his own as Aizawa recaptures Hitoshi’s attention to get said breathing steadied.

“Cut it a little close there, Shou,” Yamada mumbles from behind them, sounding about as frazzled as Denki feels.

Aizawa doesn’t deign that with a response.

The next few minutes find everyone settling again, Nemuri’s boys carrying a few chairs and cushions to the stern. Even with one of his biological restrictions erased, there’s still Hitoshi’s tail to contend with, and it’s too much hassle in the dead of night to lug him further into the boat.

Denki considers accepting a chair of his own—up until the moment Hitoshi gets his arms underneath himself and eases upright. The less bristly strands of the siren’s hair flop into his eyes, and without thinking Denki reaches, pushes the offending locks back over Hitoshi’s forehead. He drags and teases his fingers through the wet mess until it lies in short, wavy peaks, out of the way. It’s got a fascinating texture , he muses, rubbing one lock between his thumb and forefinger. Some strands like silk, clinging to the drops of water, and others thicker like the spines of fins, like his ears—

Hitoshi rumbles in a way that’s always meant amusement, but with his new breathiness it’s dragged out into nearly a moan, and Denki whips his hand back lightning-fast.

“S-sorry,” he says, face hot.

The siren tilts his head, ear-fins flicking, those lazy lilac-pink eyes heavy with question. As if such impromptu physical interactions are nothing to note, maybe even natural , and he can’t understand why Denki’s flushing pink with embarrassment.

Hitoshi breaks the shared stare only to glance around, then wriggles himself backwards so that he can remain propped up and sitting against the fibre-reinforced plastic side of the boat.

Denki turns to Nemuri, a request on his tongue – but she’s already holding two cushions out to him knowingly. He accepts them with a sheepish grin and settles down next to Hitoshi, bemusedly aware of the siren rolling a middle section of his tail flush against Denki’s calves.

Shit, he’s long. It’s noticeable more than ever with them on even ground like this. Not just the seemingly-endless wave and curl of that vibrant tail, either; sitting side-by-side, Denki finds himself looking up at Hitoshi, the siren’s sharp jawline even with the top of his head. It’s hard to believe Yamada’s casual observation from last week that the siren isn’t done growing. How much bigger could he get?

The mythical being in question catches his gaze again without turning his head fully, and smirks.

Heh. Denki’s so fucking done for.

“Ya know, Nem, this would have been a super handy thing to have my hands on a century ago!” Yamada’s holding a small, milky-white carved hoop with a reverent expression, turning it over gently in his long fingers. “Even if it only works one-way, all the time it could’ve saved… where’d you find it?”

She plucks the object from his hands. “Not your everyday human flea market, I assure you. Now, let’s see if I got my money’s worth. Fey magic’s supposed to be permanent, and all that.” With that, she drops to a knee on Hitoshi’s other side and grabs his right ear-fin—ignoring the guttural growl that has even Denki tensing in fear. “Hush, you big baby,” she tuts.

Then without another word for warning, she slides off a section of the hoop to reveal a needle-like point, and jabs said point unceremoniously beneath the cartilaginous upper curve of Hitoshi’s ear.

Denki ducks to the side with a yelp to avoid Hitoshi's recoil. The snarling siren swipes a clawed hand at his aggressor, the other curling defensively around the unwarranted new piercing.

Nemuri’s quicker than she looks, however, and dodges beyond his immediate reach with only a shallow nick to her forearm. She settles her hands on her hips. “Right from my horde to yours, you ungrateful blowfish.” Hitoshi’s noises peter out near-instantly. “That’s right. Now you see the value in my gift. You owe me one, hear?”

“What’s it do?” Denki asks, easing himself back up. He flinches when Hitoshi’s head whips around to stare at him, intense and surprised. “Are you—”

A hand—the same one that had just sliced Nemuri, he’s pretty sure—lifts to Denki’s face, settling on his chin in a way that makes his heart skip a beat. Hitoshi’s gaze jumps back and forth sporadically between Denki’s eyes and mouth. The inquisitive chirp then whispery, fluid Mermish that follows after is hesitant, unsure, awed.

Swallowing, Denki blurts, “I—I don’t understand. What did you do to him?”

Hitoshi’s smile falls, fins drooping with clear disappointment.

“You don’t understand,” Nemuri coos. “But now he does. Handy little thing, hmm? Served me well before I learned a couple human tongues.”

Oh.

Holy shit.

Denki turns back to Hitoshi, wide-eyed, a ball of warmth and hope rising through his lungs like a miniature sun. “You understand me?”

Hitoshi’s ears flare, and he smiles again, though it’s melancholy.

And Denki doesn’t need words to discern why, not this time. Even just this one change is a massive step forward for their communication, and his gratitude is boundless—but it’s also laced with chagrin. It’s great. It’s a relief. But it’s not perfect. If anything, it stokes his desperation for two-way communication, and judging by the look in the siren’s eyes, that feeling is mutual.

“Better than nothing at all,” he offers with a short laugh, leaning into the cool, smooth hand on his cheek. He touches the back of Hitoshi’s knuckles, sliding his own fingers over the interlocking scales he finds there, and lets himself appreciate the contact for a few heartbeats longer before pulling away. “We’ll figure out a way, even if it takes a bit.”

He casts a glance to Yamada, who’s already beaming with encouragement.

It brings out a shy grin; Denki ducks his head and tugs at his long side-bangs. “Gotta admit, I’m kinda nervous, my guy! Now you’re gonna make sense of my random dumbass muttering—you just wait, give it a day or two and you’ll be thinking, ‘Huh, why the shit did I ever come back to the surface for this blabby human? He can’t keep his mouth shut for five goddamn seconds!’ So you’ll protect whatever it is that needs protecting but stay clear of up here, hoping that one day I’ll stop being the puppy at the living room window watching and waiting for his bestie to come home, but I’m too stubborn to get the message so—”

Hitoshi interrupts him with a sharp cluck of his tongue and a low chirr that couldn’t be anything other than exasperated amusement, if the wry slope of his lips is to be believed. While body language and social cues aren’t entirely similar between their species, it seems Hitoshi has picked up some human expressions, as he briefly rolls his eyes upward while hiss-chirping out a short response.

Denki scowls, but it’s fond. “Hella curious to know what that meant, though I doubt it was praise,” he murmurs, to which the siren gives another sharp grin that does funny things to Denki’s insides.

“Well, there is a more permanent fix to the language problem—” Nemuri begins with a cackle, until Hitoshi tenses and Aizawa cuts across her with a final ‘drop it’ .

It’s enough to shatter their not-so-private moment of bonding, though, and Denki sighs when Hitoshi eases himself away to lean back against the boat’s wall. The scant inches between their shoulders feel like miles, which only serves to make him painfully aware of his own desperation, if he’s being honest. Bluh.

“Now that we’ve got that out of the way,” Aizawa says drily, dark gaze sliding down to Hiotshi, “It’s time to get all our information on the table. How long until the leyline wakes up?”

Hitoshi straightens and speaks; Yamada shuffles closer to Denki to provide a quiet running translation. A number of days now, the siren says. There’s no way his kin in the trench won’t start feeling that something’s changing – the coral-fins definitely will, if they haven’t already. Even with the researchers now on the hunt for him, Hitoshi can’t go far. He refuses to, a stubbornness to his chin and stare when Aizawa points out that carelessness won’t do him any good.

“You attacked their equipment. That’s going to draw their attention more than ever, and won’t give us a chance to prepare for when the real problems come hunting.”

Hitoshi doesn’t look a pinch guilty—he flicks back his ears, expression fierce. They need to back off, Yamada translates.

Aizawa sighs and settles into a crouch. “They do, yes, but we can’t make them.” He looks to his husband—mate?—and adds, “We’ll need to stage out own paper investigation in the area to cover up any fortification efforts. Keep the other researchers off our backs. Think we could sell that?”

Biting the inside of his lip, Yamada hums. “Well, the ruins are my area of expertise, unlike with the tank conundrum. My bid should hold more weight. But we’ll need our own dive teams to make it believable.”

“I could spare my boys, I suppose,” Nemuri adds.

Hitoshi bristles, showing a hint of teeth and snapping out a guttural, growling reply.

Aizawa huffs. “Come off it. You don’t have any issues with Kaminari and his friends.”

Another hissed retort, Hitoshi’s shoulders hunching a bit. Yamada doesn’t translate but he doesn’t have to; the amused chuckle suggests that the siren’s petulance is grounded in favoritism. He can almost hear the ‘yeah, well that’s different’ in the somewhat bashful flicking of fins and curling of the siren’s tail.

“It’s really not,” Aizawa says, confirming that train of thought.

The bickering continues, Aizawa even slipping into Mermish after a few more back-and-forth retorts, filling the night air with the whisper-clicking of arguments that go untranslated. Nemuri makes a purr-like contribution at one point with a sly grin, only to have both the others turn on her in an instant, and she backs out of the discussion with a pout.

Yamada’s shoulders shake with laughter. when Denki gives him a quizzical look, the man announces jovially that “Apparently we’re the only humans in the Pacific worth our salt, little listener.”

At long last, Aizawa seems to relent in the face of Hitoshi’s adamant stare, and lets out a weary groan. He passes a dull look to the rest of them before irritably turning his gaze back on Nemuri. “Which of the Midnight Boys are trained ship mechanics?”

She raises two fingers, and as if on strings, a pair of the blood-bound young men emerge from the nearby stairwell with near-vacant expressions. “Will they do?”

“They’ll have to.” Aizawa turns to Denki. “When we get back to the ship tonight, make a list of your daily tasks– and where any manuals for them can be found. Bakugou’s too, if there’s a difference. Then pack up any essentials. You’re getting a temporary switch in occupation.”

Denki straightens in his seat. A change of pace, especially where he knows Hitoshi is involved? He doesn’t dislike his job by any means, but giving up time in the mechanic’s bay in exchange for helping his aquatic friend doesn’t require a second thought— sign him the fuck up. He turns to Hitoshi, eager agreement on his tongue, when the rest of the discussion catches back up with him.

They’d been talking about diving teams.

His stare tracks back to Aizawa, and he swallows around the knot of fear that gathers in his throat, coursing panic and adrenaline through his veins. “You don’t mean… I can’t possibly… ”

“You’re not being forced to get in the water, kid,” the man says flatly, as if that were obvious. And yeah, maybe it should have been, especially coming from the man who had protested Denki’s further involvement in the first place. “But at the very least, you’ll want to stay on this boat to give a hand to the project, I assume.”

Denki nods slowly, sheepishly. “W-well, yeah. Of course.”

“Then don’t worry about diving for now. We can sort that out later if it comes to it.”

The ocean is a hell of a lot deeper than the holding tank, though, and Denki glances at the waves when the cold fear migrates down to his stomach. It’s one thing to appreciate the sea and enjoy exploring it from the safety of a vessel, using his beloved sea rover as his eyes. He’s not sure he’s keen on any more than that.

So, as neutral as possible, he offers, “Y-yeah. Maybe.”

Hitoshi curls his tail gently against Denki’s ankles, as if to say, It’ll be fine. But coming from a being born to the water, that’s biased, no doubt.

Nemuri claps her hands together. “Perfect! I’ll have the boys draw up some rooms. My accommodations may not be as comfortable as the research ship, and you’ll need to bunk up, but that’s part of the adventure, isn’t it?” She bares her teeth in a wide grin, and it doesn’t take much imagination to envision them as needle-sharp, as they no doubt once were. “Losing two, gaining five – it’ll be a right party!”

“Five?” asks Denki.

Yamada laughs. “Well, you and Shouta can’t get in the water, and I’m out of practice to say the least. But your friends have their certifications, and they’re good in our Hitoshi’s books. It’s just a matter of convincing them!”

Denki processes for a moment, then takes a deep breath.

Yeah. Convincing them.

Uraraka is easy. She’s an experienced diver, and up front recognizes this as the once-in-a-lifetime opportunity that it is, even without a full explanation. She lights up with wide eyes when Denki drops the question casually over an early breakfast that morning, the three of them squirrelled away in the mechanical bay like they’d done so frequently before Denki’s life had fundamentally upended itself over one overgrown purple fish.

“I’m sure Professor Tatsuma won’t have an issue with me taking a few days to focus on paperwork – I’ve done overtime on-call for the past few weekends.” She rifles through Bakugou’s desk drawer for a notepad and pen (ignoring his protest), and begins a point-form list. “Do you think Hitoshi would be okay with answering a few questions now that he understands us? And Mr. Aizawa—all this time—I still can’t believe it—”

“Don’t see why I should help,” Bakugou grumbles, pointedly locking the drawer and pocketing the key. “Maybe they think they’re doing us a favor, telling the truth about that hobo after all this time, but I’d bet ten thousand yen that we’re not getting the full fucking story. I ain’t leaving my work here on a whim just because the fish’s goddamn picky.”

He glares at the two Midnight Boys who are tinkering with Denki’s latest task, the pair of them for all intents and purposes completely oblivious to the rest of the room. At least their current focused expressions have replaced the uncannily polite smiles of the night before. Denki doesn’t doubt these faces are still intentionally manicured, but it’s less jarring.

“Just think, though,” Uraraka starts, tapping the pen eagerly. “We’ll be named contributors in the biggest, most important research paper to come of this expedition! All of us! Documentation about a living mer? It’ll go global, no doubt. That’s not the kind of accomplishment just anyone can put on their resume.” She winks at Denki.

Oh. He gets it.

“Not to mention we’ll be trusted allies of the mer, if everything goes well,” Denki adds, hiding his grin back at Uraraka behind a hand.

Bakugou grunts, his pen pausing over the calculation he’d been staunchly working through, gaze losing focus. “Don’t give a shit,” he mutters. His pinched expression suggests otherwise.

Almost there. Denki gives Uraraka a look , because she can press the other boy without him exploding.

She nods minutely and lifts her chin, mischief in her eyes. “That’s fair. It’s understandable if you’re too nervous to work with Hitoshi after everything. Fear is probably a norm—”

Bakugou erupts from his seat like a live volcano. “What did you say to me, Cheeks? ”

Gottem.

“Really, man, it’s okay!” Denki tries fighting back a snicker, but it’s too late.

Bakugou slams the pen down and shoves his chair back violently, giving the both of them separate murderous looks. “Tch. Get the fuck out of my way, idiots.”

“Bakubro? What are you—”

“Shut up, Creaky. I have to go pack, don’t I?”

As he storms away, Denki and Uraraka share a high-five with matching grins.

By the next afternoon, they have everything figured out. Four humans plus two ex-sirens gather on the rear deck of the Midnight Lady in various levels of exhaustion and excitement. Denki can’t help but scan the water for Hitoshi, the only one missing from their number, but the siren is nowhere in sight. He only pulls his attention away from the waves when Nemuri coos in his ear about how ‘sealing the deal’ means he’ll never have to wonder where his beloved is again.

Nope. Not touching that with a ten-foot pole. He hobbles his way to stand between Bakugou and Uraraka, fighting down a flush and pointedly ignoring the latter’s inquisitive smile.

Aizawa holds up a piece of paper with his husband’s handwriting. “Alright. Let’s begin with the state of tasks. Hizashi, have you cleared our… investigation with your superiors?”

“We’ve got this zone to ourselves for the next week!” Yamada replies, hands on his hips. “Officially, we’re here to document the ‘mysterious’ barrier that took Kaminari’s sea rover out of commission. Nezu approved it himself on the condition that he be given first look at our results.” His expression tightened. “He’s a clever one. I don’t doubt he realizes something is up, but he’s doing us a favor.”

“Hmm.” Next, he looks between Denki and Bakugou. “Have your replacements settled into their jobs?”

“They seem to be competent enough,” Denki shrugs. He knows he’ll be fixing the damaged rover while on the Midnight Lady anyways; the mechanics Nemuri supplied don’t have anything particularly difficult of his to handle.

Bakugou scoffs and crosses his arms. “If you wanna call it that, I guess. They look like damn idiots and I don’t trust ‘em not to fuck up the bigger tasks I get saddled with, so I’m skipping back each day to check in.” He tips his head sharply towards Nemuri’s seadoo and meets her gaze, as if challenging her to deny him that option. She doesn’t.

Uraraka cuts in next, bubbling with eagerness. “I’ve cleared an absence from on-call duties for the rest of the week! As long as I have space and time for my remote research, it’s all good on my end!”

“You’ll have a room all to yourself, dear,” says Nemuri. “But the boys will have to bunk up.” She talks over Bakugou’s complaint, turning to Yamada. “You’ve set up your radio recording equipment, I assume.”

“As a last resort.” Aizawa fixes her with a sharp stare.

It strikes Denki as an odd response to such a straightforward, playful hobby – but the sober, unenthusiastic expression worn by Yamada himself only reinforces it.

“It’s ready if needed,” the professor confirms.

Denki can’t help himself. “What’s so serious about the radio show? It’s harmless fun, isn’t it? I like listening to the reruns.” He glances between each of the adults in turn, only feeling better when he sees Uraraka nodding in agreement in his peripherals.

After a tense moment, Yamada ruffles his hair, only saying “I’m glad you like it, little listener!” in a less chipper than usual tone. His smile doesn’t reach his eyes for what might be the first time ever since Denki has met the man, and it’s jarring, to say the least.

He files that away for later when they’re collectively distracted by a thud at the hull. A sopping hide pouch arcs out of the water, landing with a splat and muted jingle a few feet from the edge. Moments later, Hitoshi heaves himself up after it, shaking out his hair like a wet dog and scattering seawater droplets across those nearest.

It takes him a few seconds of intense focus to switch to his lungs and remember how to breathe—and to Denki, that’s immediately relatable. The blonde can’t tear his eyes away from the siren’s form, heart stuttering at the flexing muscles when Hitoshi pulls himself bodily from the water. Seeing those brilliant scales glinting in the direct sunlight hits different.

Hitoshi is a living jewel – he should never have to hide.

Aizawa scoops the bag up and tips it over his open palm; out tumbles a number of ornate bracelets inscribed with symbols Denki vaguely recognizes from Yamada’s textbooks.

“The plan,” the man starts, “is to identify and secure anything inside the barrier that might help us. Hitoshi and Nemuri can pass through the wards on their own, and anyone in contact with them can do the same—but as a back-up, you’ll be wearing cuffs that let you come and go freely. After all, the barrier rejecting you if you need to leave in an emergency could... very well be fatal. Hitoshi?”

The siren takes the bracelets back and nicks the muscle at the base of his thumb on a sharp tooth. He smears his dark blood across the oval panels on the top of each cuff until they activate with gentle, barely-noticeable silver glows. As if absorbed, the blood vanishes.

“For the purposes of exploring, you’ll be partnered up. Nemuri—”

“I’ll take the blonde,” Nemuri offers with a wink.

Bakugou says nothing, but both of the other older adults stiffen up immediately, and Aizawa retorts with a scathing “Absolutely not. Bakugou, you’re with Hitoshi.”

The two of them let out a groan and a low warble, respectively, but don’t offer further protest.

Uraraka bounds over to Nemuri with an open, ecstatic expression. “I look forward to working with you, Ms. Nemuri! I never imagined that merfolk could switch to live among humans – do you mind answering a few questions about siren biology while we—”

Denki zones her out and makes his way across the deck to Hitoshi’s side. The merman watches him approach evenly, wearing an expression that might have been construed as bored to most others – but Denki reads into the subtle spreading of the other’s fins and smiles back in turn. Sure, the siren lacks the luminosity in his eyes and scales from the night before, but it doesn’t matter. That entrancing half-lidded gaze will never get old.

“I’ll fix up the rover before y’know it, and you can lead it around and show me all the sights, yeah?” Denki says, taking a seat and leaning their shoulders together. “It’s—it’s safer that way.” Aizawa’s implication that he could get in the water flits around at the back of his brain like a stray spark. He’d be lying if he said he isn’t curious, and he knows the grouchy old ex-siren wouldn’t have brought it up if there weren’t methods in place to keep him safe, but...

Hitoshi replies, and the hush-like roll of the words are gentle enough that Denki’s sure they don’t leave the weighted space between them. Which means there’s no hope for translation, but… that’s okay. They’ll get there, somehow, someday. Besides, the siren’s sidelong gaze deciphers it for him: I’ll keep you safe.

In a moment of bravery, Denki reaches out and pulls Hitoshi’s nearest hand into his. His heart sits in his throat but the cool scales against his palm feel inexplicably great, grounding.

“You too,” he whispers, closing his eyes.

He doesn’t see the flash of surprise on Hitoshi’s features, nor the coloring and glow that gradually rise to those dusky cheeks. He certainly misses the look shared between Hitoshi and Aizawa, who offers a slightly-raised eyebrow and barely-there smile in question.

What Denki does feel is the siren gently squeezing his hand back instead of pulling away. And that’s enough.

Chapter Text

The first two days of their paper investigation are unexpectedly lonely. That’s not to say that Denki’s ever actually alone; no, there’s not enough space on the Midnight Lady to feel cut off from everyone else. Especially when he shares a room with Bakugou, and they collectively spend the evenings gathered on the deck reviewing findings and plans for the dives the next day.

Denki knows his jealous flashes are equal parts inevitable and redundant. The only thing really stopping him from joining the others on the dives is his self-preservation instinct—which, fair, it’s there for a really good reason, and has been a worthwhile guide for the most part. He’d give it a seven outta ten. And while the others haven’t brought up the option of him tagging along since he turned it down the first time, watching the divers suit up and disappear into the deep (alongside Hitoshi, who repeatedly departs with a moody glower) is rapidly decaying the last of his resolve.

Yamada does a stellar job of keeping him distracted for a little while. He tells Denki to pull up a seat beside him on the comms and shows him the dive data as they listen to Bakugou cussing out Hitoshi at every opportunity. The one-sided conversation paints a vivid picture of their exploration, but only serves to make Denki’s envy ping louder than the intermittent radars that the communications system picks up.

Eventually Denki resorts to bickering back in Hitoshi’s stead with all manner of fish-related puns, grinning victoriously when he earns a chorus of groans (and Nemuri’s lone cackling) for his efforts. He keeps a tally of the unique threats to his well being that Bakugou offers in retort. Guy’s more creative than Denki previously gave him credit for, he’ll admit.

Still, judging by the way the other blonde goes out of his way to cook for the group of them sometimes in the downtime and evenings, Bakugou appreciates the change of pace more than he’d ever put into words.

The meals are their own source of entertainment, namely because Hitoshi seems to have absolutely no qualms about eating—nor stealing —human food these days. The first time half of Denki’s sandwich goes missing he tentatively blames it on a lapse in memory until a handful of seeds and crumbs float up to the surface near where he’s sitting.

Aizawa gives a warning about mer-unfriendly ingredients, but, predictably, Hitoshi disregards it entirely. Denki doesn’t understand the dynamic between the two of them—sometimes when he overhears the pair conversing quietly in Mermish, Hitoshi appears to hang onto Aizawa’s every word. Then other times, without warning, the younger siren will take his senior’s advisement and throw it right the fuck out nearest porthole with a narrow-eyed stare that screams You don’t control me! – not unlike half the teenage population of Japan. 

It’s astoundingly filial. He doesn’t dare mention it to either of them, especially not when Hitoshi’s barely keeping down the cheese slices Aizawa had expressly said to leave alone, and the latter is glaring at Denki as if it’s his fault that the siren has sticky fingers for anything he perceives as edible.

Hitoshi does finally learn his lesson, and Bakugou isn’t even trying to be sadistic when it happens.

An alarming dry retch followed by broken, choked-sounding hissing pulls Denki’s attention to where the fish is laying on the boat nearby. He watches, confused, as the siren blinks rapidly, dark tongue partially extended as if he’s not entirely sure what to do with it anymore.

A glance down at the plate Denki’d been ignoring while recalibrating the sea rover’s depth sensor holds the answer: two of the stuffed chili peppers are missing.

“Can’t handle the heat, ‘Toshi?” Denki asks with a shit-eating grin, taking one for himself. The fact that Bakugou’s kept the spice levels cranked down for a whole day and a half is a miracle of its own. “Guess there’s not much in the way of hot ‘n spicy down under the sea, huh?”

Sirens have perfectly functional tear ducts, judging by the wetness streaming along the bottom rims of those startled black and lilac eyes. Hitoshi splutters and wheezes, gripping his throat, then pressing at his chest, as if he’s not sure which is the worst offender. Finally, he seems to get some sort of idea for a solution, and gracelessly topples himself off the stern of the boat with a hefty splash.

Denki peers over the edge and nearly falls off his seat in hysterics at the sight of the siren open-mouth-gargling sea water for relief.

“Serves him right,” Aizawa mutters from across the way.

That only serves to intensify Denki’s laughter until the siren glares up at him with flushed-bright fins; Hitoshi resolutely does not resurface for a solid six hours.

(When he does, it’s to toss a live lobster into Denki’s lap. The screech is undoubtedly heard for miles. Bakugou snorts and cooks up the crustacean; he’s more mindful of Hitoshi’s snacking tendencies from thereon out.)

Before they hit the sack on the second day, Nemuri pulls Denki aside. Instead of taking a bite out of him as he’d expected from all of Aizawa’s warnings, she shoves a nondescript box into his hands.

“If you don’t wanna trust magic to keep you mobile down there, fine,” she says, rolling her sharp blue eyes in exasperation. “You can stop looking so stranded now. I had the boys dig that up from our storage. Should be more up your alley, hm?”

In the box is a hand propeller – and not a dated nor cheap one. He doesn’t believe for a second that it’s been in storage for more than a day at most, but when he glances up at the ex-siren to point that out and ask how she could have come by it in the first place, she silences him with a challenging leer.

He’s touched, if not a bit terrified. His questions are perfectly content to go unanswered, thanks.

He finishes repairs on the damaged sea rover the next morning. Waiting for Hitoshi and Bakugou to get back from their morning expedition has him absolutely buzzing with excited energy; Yamada helps him get suited up and Nemuri checks over the spells keeping the pressure down. By the time a familiar mop of purple hair breaks the surface, Denki’s already sitting on the edge with the propeller on his lap.

“Hey buddy,” he offers, unable to keep the giddy grin from his face as he takes in Hitoshi’s gradually widening eyes. Denki inches forward further, the water lapping up around his knees, a chill slipping over him even as the wetsuit holds the ocean’s full frigidity at bay. “Gonna need you to have my back. Just like before! Except—except not at all, shit, hah, I’m really kinda dead this time if anything goes wrong.”

He swallows thickly, aware of his heart thrumming at an elevated rate even without consulting the digital monitor strapped to his wrist, but whether it’s because of the determination in Hitoshi’s expression or the anticipation of plunging into the seemingly-bottomless blue, he doesn’t know.

Bakugou breaches a few feet away, easing off his face mask. He takes one look at Denki, slides his gaze to the fixed sea rover, and mutters, “Fucking finally. Now get in before you psych yourself out and regret it later, idiot.”

Well, if he insists.

Denki adjusts his own mask. The low, barely-audible drone of the communicator is a constant within the enclosed space, a reminder that Yamada’s got a thumb on his metaphorical (but also kinda literal) pulse. The weight of the flippers sits heavy on his toes—a last resort. Just in case.

Hitoshi slips his fingers under Denki’s hands, bracing his thumbs over the covered backs of them, and pulls gently towards the water.

And, holding his breath, Denki slips in.

Even expecting it, the initial cold comes as a physical shock; the suit only covers up to his neck, and the temperature on his scalp has him scrunching his shoulders up around his ears. His hair drifts up and around the crown of his head much like Hitoshi’s own, and he can’t help but instinctively kick to tread water until it pings an ache through his calves. He curses into the mask.

Firm hands on his shins bring that to an end. Denki lets himself go still, getting his breathing under control as the bubbles rise and clear. But the exercise in controlled inhales is all for naught, as his breath temporarily catches and stutters at the sight of his—of Hitoshi.

It’s one thing to watch the siren move within the watery confines of a tank. He was beautiful even then, despite the harsh overhead lights and the cramped space, his broad and silken lower fins stirred by the flow of the valves. The memories of their first eye contact, the exchange of names, and Hitoshi holding him are all burned into a special place in Denki’s brain, and without the tank he’d never have those, but—

But submerged against the black-blue emptiness of the sea where he belongs, Hitoshi is something else entirely. He manages to fill Denki’s sight like he owns it, vivid and sleek and powerful and in his element. The high noon sun furthers his majesty by hitting the water and casting bright, shifting patterns of light over his scales, rendering some of them a blinding amethyst.

Denki knows he’s staring down at the siren openly. He can’t help himself. Hitoshi is a masterpiece. He’s stunning.

The siren lets go of Denki’s legs and drifts away a few feet with hardly a lick of effort, gazing back half-lidded with a lazy, confident smile.

"It’s his coral-fin genes you can thank for that vibrancy,” Yamada crackles in his ear, voice betraying a grin.

Oh.

Denki’s face heats near-instantly. “I—sorry, that was—I mean—”

Aizawa cuts in next, gruff. “Relax, kid. Can’t have your heart rate all over the place like this.”

“Let him have his crush, Shou!”

Fucking fantastic, they were both listening.

He covers the face of his mask with his free hand and whines. Hitoshi can’t seem to hear the others, which is a small but blessed relief, but the mask and water do absolutely nothing to conceal his embarrassment from the overgrown fish now languidly circling him. At least he’s not going to freeze anytime soon, with mortification keeping him just this side of boiling.

Hitoshi taps two clawed fingertips on the propeller in Denki’s other hand.

Right.

For the next half-hour, Denki experiments with the device’s settings, staying in the vicinity of the Midnight Lady. Hitoshi never strays more than a dozen feet from him, putting Denki to shame with the ease and grace with which he slips through the water. Denki expects the siren to show some degree of impatience eventually, as they’re not really doing anything, but Hitoshi appears entirely content to drift along at the propeller’s speed.

Now and then a fin softly grazes across Denki’s chest and legs when his swim partner passes beneath him. Never above, only ever below, as if guarding his human from the staggering void. When it happens, he instinctively glances at Hitoshi, who without fail is always gazing right back.

It stirs a bubbly, light feeling in Denki’s chest.

Eventually, on Yamada’s suggestion, he tilts the nose of the propeller down and lets it drag him away from the light. The spells woven into the dive gear do their job to equalize and keep the overbearing pressure away as he passes fifty feet, then one hundred. The ocean below is no longer empty nor endless at that point; he can make out distant shapes of the landscape, the flitting of small fish around a deep reef, and even carved pillars far, far below.

“Is that part of the settlement?” he asks, to which Hitoshi flares his ear-fins and gestures for Denki to swim deeper.

Yamada comes over the communicator again. “Judging by your positions, you’re near the uppermost edge of it. The outskirts. There’s a long way yet to the barrier. It’s fully in the mesopelagic zone, Kaminari – you sure you want to go right now? We can get Bakugou to take the rover in your direction for an extra set of eyes on ya, but…”

Denki waits for the man to continue, yet is met with silence. “But what?”

There’s a delay. Aizawa’s the one who replies, “The other two are back at the ship already, and the rover doesn’t rise fast. If anything goes wrong, it’s just you and the guppy down there.”

“O-oh.”

“You don’t need to do anything you’re uncomfortable with.”

“Y’know, you’ve made a huge leap forward today, listener!” Yamada adds. “Why not take a breather and get back in tomorrow? You can build up to it! No need to push so far for your first dive!”

Denki pulls the propeller closer to his chest and bites his lip. He could return to the ship and test the rover during Bakugou’s afternoon dive, following along behind the other blonde and Hitoshi from the safety of the Midnight Lady’s underbelly. The experience wouldn’t be the same, but he also wouldn’t be in anyone’s way. And it would give him a chance to truly acclimate to diving over the span of a few days…

…Still, they only have a few days left, if Hitoshi’s predictions are right.

He swallows and raises his gaze a fraction from the distant, faded shapes far below to where Hitoshi waits. The siren, deaf to the chatter from Denki’s comms, tilts his head to the side when their eyes meet.

Hitoshi warbles low and inquiring. Obviously sensing his dive partner’s indecision, he drifts closer and reaches for Denki’s hands, wrapped tight around the handles of the propeller. His expression is intense, unwavering as he utters something in Mermish that ends with Denki’s own name. It feels like both a plea and a promise.

Trust me.

How could Denki not?

He smiles through the mask while finally giving the others his reply. “Send Bakubro with the rover.”

“You’re goin’ down, kiddo?”

“Yeah.” He says, flicking the propeller’s controls with a thumb. “Yeah, we’re going down.”

The descent drops the temperature and raises goosebumps across Denki’s covered arms. Bit by bit, as the sunlight’s reach falters and weakens, the visible sections of reef slope sharply down into the aptly-named twilight zone far below. Each newly-revealed ruin is a new source of excited whispering that pulls laughter from Yamada and a look from Hitoshi which Denki can only describe as… fond.

If he thought Hitoshi was sticking close before, now the mer is practically tethered to him. More than once Denki needs to yank the propeller away from trailing fins lest they get sucked up into the whirling blades that drive the small machine onwards. Hitoshi doesn’t comprehend Denki’s explanation of the propeller’s mechanics, because of course he doesn’t, but he is curious enough to cover Denki’s hands with his own now and then to steer the device in a new direction.

And if Aizawa and Yamada notice the fluctuations of his heartbeat when Hitoshi holds Denki’s hips and lets the propeller drag him along for the ride, they kindly refrain from commenting beyond a quick, generalized check-in.

While the sea rover doesn’t ascend quickly, the same can’t be said for it sinking. After fifteen minutes a louder whirring catches their attention and the newly-repaired navigator drops past them with all the grace of a boulder. Denki squawks and dives after it, fearing for its safety. Had he double-checked the buoyancy meter? Was there a fault in the gears?

No, it turns out – Bakugou’s just impatient as a default setting. The rover waits for them on a ledge near what seems to be a small undersea hill, pressing insistently against the stone with its graspers. Denki might as well be listening to his coworker’s growl of ‘Get a move on, Creaky,’ with the way the machine moves. The camera swivels to stare at them, and Hitoshi seems to bristle slightly before gliding forward and pressing a hand to one steel side of it.

The rover disappears soundlessly through the side of the hill.

Hitoshi keeps pushing it until his hand and wrist, too, have vanished into the rock, and it’s only then that Denki gathers enough brain cells to understand what he’s seeing. He recalls Bakugou’s fix-up job on one of the seafloor sweepers—it had run into something that the radar didn’t pick up, that wasn’t actually there in a literal sense.

The barrier. He’s already steering himself towards it when Hitoshi looks back, and stretches a hand forward, letting the burst of momentum from the propeller guide him to the solid-looking rock face—

Energy crackles over and beneath his skin as he passes right through the illusion, the magicked cuff on his wrist surging with sudden light. But that’s the least interesting thing to note a moment later, when he looks beyond and sees the ruins of a sprawling tiered settlement below.

At first it’s difficult to comprehend; the homes look nothing like those that Denki’s ever seen on the surface. They’re impressively large but simple in shape, round about their circumferences like spheres squashed down. Whatever material they’re built from gleams in the lights of the rover and propeller like sea shells, and in lieu of familiar doorways are large window-like openings surrounded by sea plants and coral.

The beauty of the sight is not without its eeriness, however. The dark depths cast everything into a permanent sort of shadow, and the pale, slowly-swaying plants dotting the landscape remind Denki of waiting ghosts. A layer of sediment touches every surface in sight. In the distance, he faintly sees large areas that did not escape destruction, resting like broken egg shells with no structures left standing.

And then Denki realizes that he’s never learned the settlement’s name.

He says as much over the comms, and silence persists for long enough that he starts to question whether there’s anyone on the other end. Eventually, there’s the quiet buzz of someone holding down the speaker button, and a few seconds after that he hears Aizawa.

“…Let it be lost to history,” he says, low and rough. “No amount of restoration will turn back time. If it’s going to be rebuilt, then let those who give it new life give it a new name, as well. One not stained by massacre.” The last phrase is nearly a sigh with how it’s forced out without conviction.

The response forms a lump in Denki’s throat. How easy it is to forget that one among them survived that.

Hitoshi leads him down into the settlement, following a broad path that winds between pillars and buildings alike towards the valley in the middle of it all. The structures give way to a place that immediately strikes Denki as important, if the decorative reliefs carved into the stone floor at the lowest point are anything to go by; they’re astoundingly intricate, covered in Mermish glyphs and imagery, an expanse of art all spiralling in towards one central point. There, at the core, is a series of decorative arches in a circle with only a handful left standing. The rest are clearly casualties to the mound of rubble that slid to a rest in the middle of the sunken design long, long ago.

It’s here where Hitoshi motions them to a stop, and after a beat of hesitation, casts a glance over his shoulder at Denki. His expression is difficult to read for once, and he indicates to the rubble with a sharp motion.

“What about it?” Denki asks. “Was there something there that broke?”

The siren glides his way to the base of the rubble. Beneath the nearest boulders lay interlocking stones, curving in such a way that they might make a flat hoop were they all visible. The inside edge of the hoop gives way to a small gap leading downwards into darkness. Hitoshi sticks his arm into it, grimaces, and pulls back.

“A hole—is it buried?” Denki moves closer, shining his light down into it. There’s no visible end. “Or… a passage.”

“What are you seeing, kiddo?”

“I’m not sure, to be honest! It’s a really decorated area— uh hello— ”

He cuts himself off with a yelp as Hitoshi grabs his face and leans in close, mouth beside Denki’s cheek. Holy fuck. It’s hard not to lean into him, to close that space, especially with his stomach doing flips and his neurons firing off big ol’ interrobangs at the proximity. He’s halfway through stuttering out a meek ‘ w-what ’ when Hitoshi says something loud in Mermish, and—oh. He’s trying to be picked up by Denki’s communicator.

Be still, heart. There’s no way in hell that his racing pulse can go unnoticed this time.

Silence persists once again after Hitoshi finishes speaking, and for a few moments that stretch on forever they stay as they are. There’s no way Denki can’t look at Hitoshi’s face. They’re close enough that he can see every individual eyelash, pick out the uneven texture of each tiny jewel-like scale decorating the siren’s cheekbones. Without the dive mask, all it would take is an inch, and…

“We’re sending the rover to you,” says Aizawa, startling Denki. “Sounds like it’s the old ceremonial path to the ley-line. It should lead directly to the Heart.”

Hitoshi’s fins flare—confirmation or eagerness, maybe even both—and he lifts his gaze from Denki’s communicator with a slow blink; their eyes meet. He still hasn’t moved away.

The next thing he utters feels like it’s half directed at Denki himself.

“Kid,” Aizawa sighs, and it takes Denki a moment to realize that he is being addressed. “He says he’s going to take you down there with him. That okay with you?”

Denki swallows. “D-down? Into the hole?” Under the ground, under the ocean, into the dark. A chill creeps through his limbs that has nothing to do with the temperature. “How. Um. How far?”

“…It’s not a short trip, but your oxygen supply should hold up. Is that your concern?”

“No! Well, it’s—I mean, sorta?”

“Gonna need you to calm yourself down, Kaminari,” chirps Yamada. “Let’s get that heart rate back under control.”

“If there’s another issue, speak up,” Aizawa adds.

Kaminari takes as deep a breath as his equipment will allow and squeezes his eyes shut. When he feels the light press of Hitoshi’s forehead against his own, he lets out the air into his ventilator slowly.

He’s overthinking. It’s not the same as back then, not even close.

“Bet it’s pretty dark in there,” he mumbles weakly.

There’s a short sound of disbelief from Hitoshi before light blossoms on the other side of Denki’s shut eyelids.

Right. Optional bioluminescence.

Denki squints, taking in the wondrous pattern of glow-spots across Hitoshi’s cheeks, forehead, neck, shoulders. The siren’s irises burn brighter than all the rest, scant inches away. He watches Hitoshi tilt his head to one side and raise his eyebrows a fraction, as if to say, Is this good enough?

Denki’s heart sinks. Shit, he can’t disappoint Hitoshi now. He hears the rover whirring down into the ceremonial valley to meet them, and pulls away from their close contact to stare at the small hole down into the earth.

His insides twist, but he forces a smile nonetheless. It’s easier than explaining. 

“A-alright then… let’s do this.”

Chapter Text

With each boulder carefully eased away from the pile, another metaphorical weight drops into Denki’s stomach. The hole into the earth grows and grows, and it isn’t long until Hitoshi impatiently tests the width of it again – by wriggling himself down into it and out of sight.

Even then, he hasn’t gone far; he’s still lit up like a glowstick, casting vibrant fuchsia and purple across the bottoms of the stones that continue to block most of the entryway. Denki wonders briefly if he could convince the siren to go ahead without him, or better yet, not go at all—but one look at Hitoshi’s eager, anticipatory expression when he pokes his head back up through the gap smothers that idea in an instant.

Hitoshi reaches out a hand.

Couldn’t the guy at least wait for all the rubble to be cleared? Piloting the rover, Bakugou’s going at it at a solid pace, but apparently not fast enough. Sure, the rocks and chunks of architecture have had a century to settle, but all it would take is one thing shifting the wrong way, and –

Denki fights down a wave of nausea.

The siren chirps, low and questioning, then, “Denki?” He utters something to follow it, probably some kind of reassurance, and stretches a bit further out of the hole.

Right. Okay. “Y-yeah, I’m coming,” he murmurs. He doesn’t move.

“If you’re having second thoughts, listener—”

“It’s fine!” Denki did already agree to it. Finally, after a short mental count to get his thoughts in order, he takes Hitoshi’s hand and lets the mer pull him towards the entrance.

The only struggle is the broad propeller, but Denki refuses to let it out of his grip, much less his sight. His heart rate monitor flashes with warning when he eases himself through the gap. Before anyone can comment on it, he forces a laugh. “So it’s gonna be a vertical trip, huh? Hah, um. Exciting.”

“The protections on your suit should help with any vertigo,” Aizawa points out, his voice crackling slightly more noticeably than before through the comms. “If you feel at all like you can’t continue, come back up immediately, kid. Hitoshi won’t judge you for it.”

No, but he’d be a dozen kinds of disappointed, Denki mentally shoots back. Still, he hums acknowledgement of the suggestion and turns the nose of the propeller downwards. Then he cranks the headlight on it up as high as it’ll go.

It’s not a straight path down and he’s not sure if that makes the whole thing better or worse. About fifty feet in, the tunnel swerves sharply to one side. The underwater haze makes it difficult to even see that much; gravity disorients him further. It’s only when Hitoshi enters his line of sight again, swimming languidly downwards towards the turn, that Denki clues back in and follows.

Even from a few feet away, it’s clear that the siren is brimming with excitement, perhaps bordering on impatience—this is what he’d spent all this time seeking, right? For the first time since they’d gotten in the water together, Hitoshi drifts ahead, mapping out the lowest point Denki can see. His upper half disappears around the curve. Denki tries to keep the thrum of anxiety down, focusing on the gentle swish of Hitoshi’s fins and the way his bioluminescence paints the rough-hewn walls of the tunnel with soft light. But…

“Hitoshi?” he calls, hating the tremor in his voice. “D’you mind staying—”

A crack echoes through the water from high above, followed by the clatter of stone on stone, and Denki’s stomach plummets.

He has enough time to swing himself to the side with a panicked, painful kick before the pebbles and grit rain down on him. They pelt his suit and clang noisily against his tank and mask—he closes his eyes—

Sero may have his doubts, but Denki’s determined that they’ve found it this time. It’s their seventh caving attempt of the summer—and probably the last, as they’re leaving the coast in a week to take the entrance exam for the premier magic academy in Japan.

Below the earth, magic thrives—not like the watered-down sparks that Denki has dabbled with in a pale mimicry of mythical beings. It’s palpable, living, something that endlessly fascinates him. He’s been mapping the ley-lines on the coast for over a year, cross-referencing with the underground systems. This beachside cave is his last chance to tap into the real thing before competing to let his limited human affinity for magic shape his future.

It’s basically a given that they’ll get in if they can take a piece of the ley-line for themselves, he tells Sero.

He’s fifteen, and whether they call him cocky or not, he knows this one’s the real deal. He’s sure of it.

Denki shoves away the hands on his shoulders—he needs his balance—where’s his centre of gravity? Everything’s wrong and off-tilt, he can’t find his footing, where’s the fucking ground?

He can’t see, can’t breathe.

Sero makes a joke about dwarves, or something dumb like that – Denki’s not really paying attention. He’s too wrapped up in the static-like sensation across his skin growing stronger as they descend. Humans might not be born with magic, but he’s a good example of one with an affinity for wielding it anyways. He whispers an incantation and lets lightning dance between his fingers. It comes so easily down here.

Take that as proof he’s right about this place, he laughs. He releases the lightning in a line down into the chasm beside them.

And then the world shakes and roars.

Denki’s foot slips on a patch of sandy rock. The rope around his waist is too well-used; he has dismissed Sero’s concerns about it one time too many, it seems. It’s too late now.

He plummets into the lower caverns. And as he falls, the ledge he’d been on cracks and topples after him. Even before he hits the ground, he knows what comes next. It’s inevitable.

Still, he’d never imagined pain could feel quite like this.

He’s up against a wall, still blind, still gasping desperately for air. Trapped. One ear fills with the crackle of static and choppy voices asking him what’s going on. He yells, voice breaking, and the weight holding him still flinches back.

His eyes open, but what’s in front of him doesn’t reconcile with the terror in his veins nor the images in his brain. The other’s face is too close, Denki can’t—

He gets a hand under their chin and shoves them away, reaches for whatever is making it hard to breathe. A mask. He scrabbles for the edges of it but large, cold hands clamp down over his.

“L-let me go—”

“Den—”

—ki?

Sero calls his name, over and over, but Denki is silenced by the agony rampaging through his back and legs. His friend’s voice grows increasingly panicked and teary, echoing in the impossible quiet that follows the collapse. Eventually a loud enough sob tears from Denki’s throat unprompted that Sero gets the message.

He’s going to go get help, he tells Denki, and disappears before he can hear the hoarse protests.

“ Kid— ”

His heartbeat thunders in his ears. Too fast. It’s overwhelming, competing with a crackling static barely recognizable as words, which only worsens when Denki slams his head sideways against the stone. His scalp blooms with pain.

He’s going to either be sick or pass out from lack of air if this keeps up. Why is everything so fucking heavy? He’s living in slow motion. Can’t escape. Can’t breathe.

Denki kicks out at the person restraining him. Pain wrenches through his legs and the light falters, plunging him into darkness. He chokes on his next inhale.

Sero took the light with him. That’s the worst part, Denki thinks as tears make tracks from the corners of his eyes, down over his cheekbones and into his hair. He can hear what’s approaching, feel it, but his wild-roaming gaze finds only black.

He knows the dangers of caving near the shore; he knows that when the tide comes fully in, he’ll drown. The sea licks at his shattered legs, numbing them. Its tidal lullaby shushes Denki’s terror with its gentle push and pull until his sobs peter out into shaky breaths. It promises him mercy and peace. The water rises.

He begs it for another chance.

A small crack in the cave floor near his cheek begins to glow, as if to say, I’m listening.

Desperate, shaking, he grabs a shard of rubble and scratches at the crack until it’s a patch of subtly-glowing iridescence the size of his thumbnail. The light may be faint, but it’s all he has, and it brings on a fresh wave of tears. Out of his mind, he apologizes to it for coming here, shares his fears, promises he’ll stop messing with magic—

It can take every bit of it, take his affinity, he’ll never use magic again, just please don’t let him die here —

There’s music—singing. It’s low and crooning, a note of urgency below the soothing trill.

                 relax – breathe – relax – stop struggling – give in

His body listens, and his face falls against a strong shoulder. A hand keeps him pressed there; another braces over his hips, pinning him. But it doesn’t feel entrapping, not now.

Adrenaline gives way to exhaustion. He slumps into the other person’s— Hitoshi’s? —grip.

Then they’re moving. It’s hard to get a sense of direction, and Denki is still mentally clambering down the side of that absolute mountain of brain-disarray, so he can’t do much more than cling back to Hitoshi and get his mind into some semblance of normal. He’s lucid enough to recognize the panic attack for what it was.

Hitoshi’s siren-song wraps around him like a blanket, keeping him from falling back into terror even as he feels the scrape of stone over his shoulders when the mer wiggles them through a partially-collapsed section of the tunnel. Down, then. They’re still going down. Does the path ever end?

The comms in his ears have gone silent save for the faint buzz of a dead line. They’re out of reach of the others.

                 relax, Denki –

He closes his eyes.

Time falls away. At some point he grows aware of a pressure deep within himself; it hums through his veins and shivers his bones, fills him with inexplicable heat. Goosebumps rise over his skin beneath the wetsuit. It’s not Hitoshi’s doing, he doesn’t think – this is bigger than the song. It’s around him, around both of them, all-encompassing. Whatever it is, it feels good.

Distantly, he recognizes the moment they turn, Hitoshi using that powerful tail of his to change their course around a U-bend and shoot upwards.

They breach the surface in a room that feels like sunlight. He’s dragged out of the water, the mask pulled away. Hitoshi’s skin is warm for once where it presses against Denki’s face.

                 safe now

The siren whispers his name into his cheek, over and over again, and the lull of the song fades.

Unconsciousness follows soon after.

Hours pass. Although he can feel its power, the sea pushes and nudges but never swallows him.

According to Sero, the rescue team that searches the cave when the tide recedes expects to stumble across a cold body. When they instead find Denki half-submerged on an outcropping, legs mangled but very much alive, they can’t make sense of it.

The stone beneath his unconscious form radiates warmth and gentle light.

His rescuers call him blessed as they pull him up.

But he just feels empty.

 

Denki tastes the magic saturating the air long before he opens his eyes.

He also acknowledges the weight and curve of Hitoshi down his side, beneath his aching knees, one of the siren’s arms pillowing his head. Soft, controlled breaths brush gently at Denki’s crown, stirring his salt-stiff hair. A long-fingered hand rests on his chest. Flat over his heart. Monitoring.

His throat aches like motherfuck, but that doesn’t stop him from taking a gulping, shaky inhale when everything catches up to him at once. He cracks open his eyes. They sting, and it takes a few attempts to clear the wetness, but then he’s greeted by the sight of Hitoshi’s collarbone, still lit up with bioluminescence even after… wait, how long has it been?

The siren’s skin is dry and unusually warm, almost matching the heat radiating from the pale stone beneath them. His chest rises and falls steadily, but not deep enough for sleep, Denki’s pretty sure. Apart from the sounds of their breathing and faint echoes of dripping and trickling water, no noise pervades the space they share.

He breaks it with a whisper. “Hitoshi?”

Hitoshi stiffens at first, then bursts into movement, maneuvering onto his elbows and leaning over Denki. His hands brush Denki’s cheeks, collarbone, chest—almost desperate in how they’re sweeping over him to make sure he’s okay.

Denki’s assurances fall on deaf ears up until the siren touches his knees—and pain flares up his nerves like wildfire, startling him into a gasp. He faintly recalls bashing at least one of them into Hitoshi himself, or a wall, or maybe both. Probably both.

Still, Hitoshi yanks his hands away, distraught.

“I’m s-sorry,” Denki hisses.

But the siren shakes his head quickly, fins flicking down and remorse written clear across his features. He cups the side of Denki’s face, stroking a thumb-pad across his cheekbone. “Denki,” he says, voice rough, “Ah’m… I-em sorry.” He follows it with a string of Mermish and a long sigh. His weary gaze never strays from Denki’s own even as he slowly rolls back onto his side and settles his head in a tired tilt against the stone floor. The light of his markings wavers, dims, before gradually steadying.

He looks absolutely exhausted, Denki realizes. “Have you—have you been glowing this whole time?”

Hitoshi slow-blinks, and his aurals flare weakly.

Denki’s throat tightens. “O-oh.” A confusing wave of emotion boils up in the span of a second, gratitude laced with relief and worry and so much else. “You don’t ha— y-you can stop—” He’s shivering again, but not from the cold; guess the downswing of the panic attack was unavoidable after all.

He takes a shuddery breath— “ T-thank you —” and the tears spill over without mercy.

Hitoshi drops the bioluminescence with a relieved sigh and pulls him close, murmuring into his hair.

Denki must still be recovering mentally, because as the whispery sounds bounce and echo around their small, sun-bright chamber, it’s as if he can understand what the siren is saying.

He cries quietly save for hitched breaths and stray hiccups, listening to the gentle words that take shape and sound at the distant edges of his hearing. They remind him of siren song, but without the firm grasp around his mind or the fog of dissociation to cloud his other thoughts. The speech comes in broken fragments that somehow, inexplicably, he understands. ≈ …safe… I am… regret… when... ≈

Denki turns his unfocused gaze to the domed ceiling of the chamber. The pale walls glow from within, pearly and iridescent. Scattered throughout them are countless little gemstones in a myriad of colors. Some are grouped together in twos and threes, others pressed into patterns in larger numbers. They continue down beneath the surface of the water, even more numerous and shining brightly as if whatever fueled the light in the walls is passing through into each and every facet.

Magic, he realizes. They’d been heading to the heart of the ley-line. What else could this room possibly be?

Eventually, when the tears stop, he eases himself up onto his forearms and finally struggles to sit. Hitoshi moves with him as much as he’s able, never completely breaking contact, as if he thinks Denki might fall to pieces should they not be touching. Denki isn’t certain enough to dispute that theory himself, and besides, the proximity is more than welcome.

But he knows Hitoshi’s filled with questions he can’t easily ask, if the concerned intensity of his gaze is anything to go by. And Denki’s not made of glass; he doesn’t want Hitoshi to see him that way any more than he already does. It’s not worth dancing around the explanation for what happened back in the tunnel.

“The falling rocks triggered it,” he says quietly, though in the heart chamber the admission echoes back as if shouted. “And I guess the darkness didn’t help. It—it reminded me of my accident. When my legs got wrecked.”

He runs his hands down his shins. The braces on his left side are janky, broken, but not beyond repair. He’s almost afraid to touch his legs with how much they ache and burn, but he’s mostly sure they’re intact. He clenches his jaw and feels along the front of the bone just in case. His knee pains are sharper. They’ll need to be iced. But he’ll be fine.

He’s still alive.

Denki swallows. “I thought I was gonna die that day, y’know? Cold and crushed and—it fucking sucked.” He tries to laugh, to diffuse the dormant terror threatening to choke him, but it comes out strained. So he takes a deep breath and runs a shaky hand back through his unpleasantly-stiff, salt-coated hair. “Still not really sure what happened! Something down there must’ve been listening. We struck a deal of sorts, a-and, well. It saved my life.”

In exchange for his affinity. And with that, the dreams he’d held for over a decade. He’d come so close to touching the ley-line back then, to tapping into its magic to boost his own, only to have it all taken away.

He looks up at the mosaic of gemstones in the walls and ceiling. Now, that magic gleams and hums within every atom of this space. Entirely inaccessible.

Stretching a hand towards the nearest wall, he brushes his fingers over the glassy, rippled surface. It reminds him of the inside of a conch shell, except for the unexpected static-like prickling sensation that buzzes over his skin on contact. It’s painfully, achingly familiar of the part of him that no longer exists.

He forces down the lingering grief. “This is the heart?” he asks, and receives a hum in confirmation.

Hitoshi slides closer to the wall, carefully tugging Denki with him. ≈…when… feel… attune, but… can’t understand…≈

“I do,” Denki says quickly, suddenly, causing Hitoshi to glance over in surprise. “I—bits, I think I’m making out bits of what you’re saying?”

Hitoshi stares at him, bewilderment arching his brows high. After the weightiness of the last discussion topic, this hits Denki as oddly funny , and he doesn’t fight the grin nor the inevitable laugh that unfurls like a flower blooming.

The siren’s fins quiver. Denki’s starting to recognize the meaning as curious, or maybe hopeful. ≈…don’t… Mermish?≈

“I hear both, I think? Like an echo—I thought I was just imagining it originally, but if it’s the heart’s magic—"

Hitoshi surges forward with a wordless trill, pressing his forehead to Denki’s.

It’s like his previous experiences with the action but on goddamn steroids. A rush of emotions that aren’t his floods the forefront of his awareness like seawater, confusing and foreign. The soothing undertone remains, sure, but the onslaught of Hitoshi’s feelings is overwhelming. Denki freezes, tenses, holding his breath—he swears he’s experiencing every moment of relief and delight and adoration that flickers through Hitoshi’s mind—

But it must go two ways, because the siren chirps—Denki can feel the accompanying embarrassment clear as crystal—and the tidal wave pulls back until Denki no longer feels like he’s drowning in a maelstrom.

Hooooly shit.

“Sor-ry,” Hitoshi says in broken Japanese, then repeats in Mermish. The pattern of speckles across his cheeks glow vividly; Denki’s now certain that it’s the siren’s equivalent of a blush. In fact, despite his strange eyes, exotic coloration, and the visible lines of his knife-sharp teeth, Hitoshi’s expression has never been so immediately relatable. So flustered. So pretty .

Denki wants to kiss him.

As soon as that thought crosses his mind, he reels back a few inches in shock.

He does? He does . He wants to kiss Hitoshi. His heartbeat hammers with the sudden realization, beating so furiously that he’s surprised it’s not audible in the quiet of the chamber. His face warms in an instant, anticipation hot in his chest. When did his feelings turn so mushy and… and romantic?

They could do it—they could kiss, right here. Nobody to walk in, or come over the comms, or one of a million other cliché interruptions that Denki has always fully expected to happen to him at a time like this. Wouldn’t be his first kiss or even in his first five, but somehow those pale in comparison to the thought of a kiss from Hitoshi—wait.

…Do merfolk kiss?

His gaze is drawn back to those teeth. Not exactly conducive for make-out sessions.

Hitoshi must get a different idea for why Denki is suddenly staring at his mouth, because he smiles—putting his fearsome chompers on full display—and flushes darker. ≈…we can… gifts of… complete, and… attune…≈ he continues, but this time the words are too disjointed for Denki to make sense of, which must show on his face. Hitoshi swallows and gently touches Denki’s forehead with his fingers. ≈…can… again?≈

“Yeah,” Denki answers quickly, and moves in to meet him halfway.

The mental connection is more controlled this time, like a stream sliding between river-stones. Denki watches as Hitoshi’s lidded gaze relaxes; the following sigh of relief feels as if it rolls through both of them. The fondness is still very much present but not overwhelming; Denki lets it wrap around him like a blanket.

≈This is better,≈ Hitoshi murmurs.

But Denki doesn’t answer at first, because back in this position they’re close enough for Hitoshi’s breath to skirt across his lips and chin, and as such his thoughts immediately gravitate towards his newfound desire to close the gap between their mouths. He has to chase that thought away with a broomstick real fast when he remembers their current shared mind-space.

Then he registers the statement properly. “I—I can hear you,” he whispers wondrously. He raises his hands to cup Hitoshi’s cheeks. “I understand —oh my gods. Say something again.”

The siren’s grin widens between his palms. ≈Awfully demanding for a kelp-brained walker.≈ But despite his scoff, a pleased warble punctuates Hitoshi’s words. One hand settles comfortably on Denki’s hip. His next words emerge far more gentle. ≈But I guess you’ve earned it. Hi Denki.≈

Denki’s breath hitches—no, he will not cry again right now, he tells himself hopelessly. He fights the urge by inhaling deeply, letting the siren’s unspoken but thoroughly fond amusement wash through him. It’s enough to pull another short, surprised laugh from Denki’s lips.

“Damn right I’ve earned it!” he retorts. “You don’t even—I’ve been imagining our first real conversation since the day you gave me your name, you know! This is a big deal! And—and you started out by insulting me!” He pulls away from their contact just long enough to fully emote his feigned distraught at that fact, only for his heart to jackhammer again at the slow spread of Hitoshi’s butter-soft grin.

Holy fuck he’s in this deep.

Hitoshi tugs him back in; their noses brush. ≈Keep blowing bubbles about that then, not like we’re on a time limit or anything,≈ he teases. Hopefully he’s oblivious to the raging fires that are Denki’s cheeks. ≈Your not-actually-a-pod is no doubt puffing as it is. ≈

Right. Denki can’t imagine what the others on the surface thought of the communication line going down, especially when the last they’d heard was likely his own panic and Hitoshi’s Song. There’d be time for apologies later, though. Right now…

“How is this even possible? Me understanding you.” he asks quietly.

Hitoshi takes one of Denki’s hands and holds it against the shell-textured chamber wall with his own, pinning it there, letting the gentle static sensation dance over the both of them. ≈What do you know of Chaos?≈

Denki hums. “The rawest form of energy. But not even you can interact with—oh.” He distantly recalls Yamada’s words, back when he’d first learned about Hitoshi’s goals. “Heart chambers are where it’s converted into usable magic. Right?”

≈Yeah. But Chaos itself is the answer, I think. Its existence follows no laws. It changes all it touches—breaks down, blurs, twists, reshapes.≈ He curls his claws against the wall, into the grooves between Denki’s fingers. ≈Sentient, in its own way. Only held back by the few points where it can touch this world. In here, it’s close. It listens.≈

The chamber no longer seems quite as empty as it had five minutes prior. Denki breaks contact to look around at the gemstones in the walls, imagining them as a thousand gleaming, glittering eyes. It raises the hair on his arms and the back of his neck, but not with fear. He’s safe here. Hitoshi had said as much.

“So it eavesdropped, then decided to give reality a bit of a nudge? How rebellious.” Denki quirks a smile and raises his voice. “But I’ll take this over total privacy any day.”

Hey Chaos? Feel free to third wheel anytime. Number one wingman. Wing-entity? Whatever.

Hitoshi huffs and pulls him in once again with one large palm cradling the back of Denki’s neck. Even though it’s not for the mouth-on-mouth action Denki’s heart keeps jumpstarting in anticipation of, the gesture on its own makes his knees feel weak. Thank fuck he isn’t standing.

They’re not meeting straight-on this time, and the light fluttering of Hitoshi’s eyelashes tickles his temple. When Hitoshi speaks, it’s a rolling Mermish murmur right by Denki’s ear. ≈I didn’t bring you down here for privacy, you know.≈

Holy shit. Denki’s heart fucking gallops.

≈I want you to attune to the ley-line.≈

Oh. Okay. Easy, boy. Denki clears his throat twice before replying. “A-attune me?”

The aural fin in his sight flares a bit. ≈So you can feel it like we do.≈ He tilts his head to meet Denki’s gaze again, the weight of his own impossibly intense. ≈Nothing to be afraid of.≈

Denki swallows. “Do I have to use magic?” He’s not ready to admit that impossibility.

≈No. I’ll handle that.≈ Hitoshi leans back, his free hand slipping up to Denki’s jawline and tugging inquisitively at the long bangs that hang there. ≈…need…≈

“Wh—my hair? Noooo way. You can have more blood.”

The siren gives him a flat look. Yeah, okay, priorities and all that.

“Really man? You’re gonna do this to me?” Denki whines, running his hand back through the strands as much as he’s able. Still rough-textured from salt, it feels kinda nasty, in all honesty. Hitoshi’s hand joins his, carding at the back of his head, claws gently scratching his scalp. “Fine, just… not from somewhere too obvious— ah —Hitoshi! ”

Their foreheads knock again briefly, long enough for the siren to relay a note of apology and a teasing, ≈It will grow back.≈

He closes his palm around the sliced-off lock of blonde hair and moves away again to murmur what must be an incantation, as it doesn’t translate even the slightest into Japanese no matter how much Denki tries to pick apart the echoing sounds. When he reopens his hand, a small golden gemstone sits bright against his dusky skin.

“…Not what I expected,” Denki admits as it’s pushed into his palm.

Hitoshi smirks and repeats the action with a section of his own hair. His gem is purplish-black, smooth to Denki’s many-faceted one, and when Denki brushes the pad of his pointer finger over it he swears he can feel a vibration. Further proof that every part of the siren is inherently magical, he supposes. 

He turns his own gem over in his fingers, wondering. “What next?”

In lieu of a verbal reply, Hitoshi circles Denki’s wrist with slender fingers and brings his hand closer to the wall. Right—the wall covered in countless other gems. But beneath Denki’s touch earlier, it had been plenty solid, so how—?

Hitoshi huffs in amusement, or perhaps impatience, and presses his own gem into the pearly-white ripples next to Denki’s hand. The wall accepts the stone like softened butter.

A soft trill of contentment pulls from the siren, whose eyes lid and fins flutter. The sight bewitches Denki; for a long moment he forgets his own gemstone as he scrambles to immortalize the expression in his brain. He’s never seen Hitoshi so at ease, as if drifting in the gentle place between sleep and wake, unguarded and vulnerable. Maybe he’s the only one ever to see this. 

The thought burns in his chest, in his eyes—he doesn’t know how to address that privilege. It ties his heart in knots and brings up a fresh wave of ‘kiss him, kiss him!’ echoing like birdsong in his brain.

Instead, Denki catches his breath and pushes his own gemstone into the wall next to Hitoshi’s, sliding it so the two of them touch.

And suddenly—though he’s not quite sure how to explain the sensation—he knows he’s no longer alone in his mind. Something inexplicably powerful has turned its gaze his way; the weight of its presence is staggering. 

He closes his eyes on instinct, this brand-new sixth sense so potent with feedback that anything from the first five threatens to overwhelm him . He feels like he should be praying, but he doesn’t know who to, or what for.

But the presence is patient. Ancient, curious, and waiting.

Impossibly familiar.

A spark of recognition comes at last, enough that it stutters his heart and sends him back into the cave for a split moment of memory. No fear, this time—only gratitude.

He bows his head. Thanks for giving me a second chance, he thinks. For letting me experience any of this at all.

The presence lingers for a few seconds more, then withdraws.

Denki too pulls back after a moment, eyes slipping open to gaze at the yellow and purple stones nestled together in the wall. It’s only when he feels Hitoshi’s thumb brush questioningly over his cheek that he registers the wetness there.

“And here I thought I was all dried up,” he laughs. “Really, I’m fine, just—that was hella intense, y’know?”

Hitoshi tilts his head, brows pinching in confusion. Denki doesn’t resist in the slightest when the siren pulls him in.

≈You feel it now? The ley-line?≈

When Denki chases the sensation the presence had left behind, he finds what Hitoshi must be referring to: that raw sixth sense in the backseat of his mind. Barely noticeable when he isn’t looking for it, but when he is, it sweeps quietly like a gentle tide.

“Yeah, I feel it,” he murmurs. “It’s...” Incredible, he wants to say, but that doesn’t do it justice. 

Sentient. Powerful. Exhilarating.  

He swallows. “Aware.”

Hitoshi hums agreement, wearing a soft, amused grin. ≈Obviously. And it’s still waking up. When it manifests, you’ll understand.≈

“Understand what?”

Hitoshi blinks slowly. In an instant, Denki is hit with a fresh tidal wave of the siren’s emotions as the previously-built caution is briefly peeled away. It only lasts a moment, and the whirlpool of thoughts and feelings twists too quickly to pick out specifics, but beneath it all is the steely resolution to protect. The fierceness of that resolve is staggering—like a command built into Hitoshi’s very soul.

 Then Hitoshi sweeps it all back behind the invisible curtain and lets Denki breathe again. ≈You’ll understand,≈ he repeats. ≈But for now, we should surface.≈

Denki tangles a hand in Hitoshi’s hair before he can pull away. “Wait— am I… am I going to stop being able to understand you?”

He’s given a melancholy smile. ≈...Yeah, probably. Anything you want to know while we have the chance?≈

Gods, what doesn’t he wanna know? Not for the first time, Denki bites back his frustration about the unfairness of it all—but judging by the apologetic softening of the siren’s gaze, it doesn’t need to be put into words. 

“I dunno, it’s just… there’s a million things I want to ask, right? I want to know all about you. Where you came from, what you like, h-how—” Denki chokes on the phrase, face hot. “—er, how y-you see the future playing out…” he peters off, noting the faint glow on Hitoshi’s own cheeks.

≈...Where I came from isn’t as important as where I am,≈ Hitoshi says quietly. ≈For now, it’s irrelevant. I like… exploring, I guess. Discovering the steel walker homes — uh, ‘ships’? — that settle on the bottom. Finding things in them. And… I like your not-a-pod. Sosvii Aizawa is reliable, but Yamada is clever and creative. They make good mates.≈

Denki’s belly swoops at Hitoshi’s casual use of the term, but if the siren picks up on the reaction, he doesn’t say anything.

≈The healer asks a lot of questions, but she’s nice. The angry one — basically the walker embodiment of a volcanic vent? He can get netted.≈ There’s a wry, playful twist to his lips.

Denki glances at his hands with a smile of his own. “Yeah, they’re good people. Uraraka’s a sweetheart, and Bakugou’s pretty cool once you get past his explosive personality. Can’t ask for better friends.” 

≈And you.≈ Hitoshi’s Mermish cants lower, smoother. ≈I really like you.≈

Denki takes that like a punch to the gut, despite how damn obvious it should be by this point. He laughs nervously. “W-well that’s good, ‘cause uh, I really like you too.”

Hitoshi sounds impossibly smug in both languages as he replies, ≈I know.≈ Still, his expression is fond, all soft lines and slow movements as he pulls Denki bodily closer as easily as one might move a doll. 

It’s times like these when Denki’s not sure where the line between platonic and romantic is drawn for the mer, to say nothing of all the touches and looks that he absolutely would consider intimate in any other situation. Their foreheads already rest against each other, so Hitoshi’s actions practically drag Denki half into his lap. 

And Hitoshi looks content with just that, still gazing evenly as if he isn’t the cause of the rapid-fire heartbeat in Denki’s chest. He must feel it, surely. 

≈As for the future? I’m not going anywhere, Denki.≈ From Hitoshi’s chest comes a sound Denki’s never heard yet— a gentle crooning that resonates reassurance. He speaks over it, Mermish harmonizing with the noise like a Song without commands. ≈Everything I need is right here.≈

Denki’s heart feels like it’s ready to burst. He could mean the two of them, sure—but maybe he’s referring to the ley-line and its magic, this long-dead settlement that he wants to rebuild, countless other things. He has to ask, but can’t bring himself to say the ‘m’ word, knowing all the weight it holds—

Hitoshi suddenly sits upright, nearly toppling the two of them as he does so. ≈...Barrier… coming,≈ he murmurs, before remembering the limitation and knocking his head to Denki’s. ≈They sent the finless witch down. More worried than I thought; we should go.≈

“Right,” Denki says. He picks up his headgear and turns it over in his hands. “Well… this was great. I never thought I’d get to… y’know.” He pulls on the mask and adjusts the suction, giving a few test breaths while Hitoshi watches. Knees still smarting terribly, he inches towards the water, letting out his breath once he’s finally submerged to his shoulders.

Hitoshi takes one last opportunity to dip them together. ≈We’ll be back. I promise.≈

Denki half-grins. “I’ll hold you to that.”

They’re alright. Shouta plans to strangle the two of them for staying down there without providing an update, but for now, he’s still getting over the bone-deep dread of the last hour and a half. The lingering stress sits like an iron cage over his chest, and it’s only Hizashi’s hand rubbing between his shoulder blades that’s keeping him sane.

At that moment, when the communication lines cut to the sound of Hitoshi’s Song, there was nothing, nothing Shouta could do.

He was sure they’d lost the kid.

Judging by the shaky events Kaminari relays as Uraraka wraps him in a blanket and Bakugou lays spell-heated hands on his shoulders to speed up the warmth, it was a close thing. Hizashi asks the questions, steady and placid like Shouta can’t be right now, and before long they have the whole story.

The whole story. He’s going to have a word with the damn kid about honesty and the dangers of facing post-traumatic triggers unprepared, mark his words. For now, though, he watches the young human and his friends head below deck, the troublemaker in question glancing over his shoulder at the last moment.

Hitoshi chirps a casual farewell, relaxed and unbothered where he’s sprawled at the edge of the deck. As if he could do no wrong. As if it were just another uneventful day drifting by with the tide. As if he hadn’t nearly let a human die on his watch —

Shouta gets to his feet, fists balled and growl barely contained as he approaches the younger siren like a rolling storm cloud. Hitoshi has the decency to flinch when he sees him coming, but it’s soon replaced with a defensive, steely stare.

≈Tell me that you acknowledge how damn lucky you were he survived,≈ Shouta snaps. ≈How narrowly you avoided tragedy, Hitoshi, because you’re a bit too comfortable looking right now, to me.≈

Hitoshi’s aurals flick back, irritated. ≈He’s fine, isn’t he? Get off my back.≈ He hauls himself up onto the edge of the rails.

≈Oh no you don’t.≈ Shouta surges forward, anger at a boiling point. ≈Stay where you are, I’m talking to—≈ He’s caught around the middle by a set of arms. “Hizashi, let me go—”

Hitoshi disappears with a splash.

Shouta grits his teeth.

“Give him a break, Shou,” his mate murmurs into his neck. “He reacted pretty well, for the circumstances, don’t you think? Surely you don’t really blame him?”

Deep breath. The stress-cage isn’t going anywhere anytime soon, but there’s logic to the point. Shouta relaxes his shoulders, tips his head back a fraction. “No. I don’t.”

“Should I bring him back?” asks Nemuri, floating lazily in the currents on the other side of the rails. 

Shouta shakes his head, sighing. “The guppy’s too stubborn. Whatever happened down there has him feeling invincible, it seems. He won’t listen.” He runs a hand through his hair. “I’ll apologize later.”

“Mmm.” Nemuri eases up onto the lowest rung of the railing, arms crossed for stability. Blue and black scales shimmer over the majority of her visible skin. Even that has taken on a tint of navy. 

Once again, her appearance reminds Shouta of a time long past. It’s jarring, borderline uncomfortable. He turns his gaze away.

She huffs. “Why is it you never came back to the water, Shou? I built up a resistance to its call by giving into it a little bit each day. Couldn’t you have done the same?”

Shouta says nothing. He feels Hizashi tangle their fingers together.

“No, maybe not,” Nemuri continues. She tilts her head. “You’re too far gone. You shouldn’t have let it get this bad.”

“Nemuri…” Hizashi warns, at the same time Shouta himself snaps, “Drop it.”

But it’s never been that easy— not with any of them. “Tell me why, then,” the infuriating sea witch presses. “Why did you wait all this time to come home, Shouta? Is it because of Oboro?”

“Don’t talk about him.”

She clicks her tongue. “You have no right to demand that, you cantankerous fin-biter. He was our friend too.”

Guilt lodges itself like a physical presence in his throat, enough for him to spare a glance at Hizashi. It’s not like his mate to be so quiet, but maybe it’s because it’s the first time they’ve breached this topic in… well, forever. Hizashi’s looking right back at him, gentle encouragement in his gaze, but Shouta can’t find a way to respond.

Nemuri, however, is ready with another blow. “You see him in the little half-breed, don’t you?”

There’s no stopping the similarities that come to mind. Differences too, sure: Hitoshi will never be an open, enthusiastic, coral-raised beacon of kindness, the kind of mer that infects others with hope and serenity by virtue of his very presence. But stronger than that is their shared brand of determination, unbridled confidence, and a penchant for self-sacrifice—

Shouta shuts that train of thought down with a clench of his jaw, taking a deep, steadying breath. “Wish I didn’t,” he admits quietly.

A few minutes pass in relative silence, Nemuri sinking back into the lapping waves, floating a few feet out on her back.

“Oboro’s not gone, you know,” she says at last. “Maybe it’s not the same, but…” she raises a hand, looking at the water sparkles upon the scales there, glinting in the dying light of the afternoon. “I can feel him. He’s everywhere, down here.” Her eyes fall half-lidded, a note of sleep touching her voice. “A memory in every tide.”

Shouta’s memories steal back to the tank on the Shinkai Maru, the familiarity of the magic present even in that small piece of the sea.

“You asked me why,” he mutters, loud enough for Nemuri to hear. “But it seems you already have the answer.”

He squeezes Hizashi’s hand, then pulls away, trudging back towards the below-deck. 

Chapter Text

Dawn has barely begun to flex golden claws at the low-lying clouds when Shouta emerges from below-deck the next morning. He stares at the water for an eternity of a minute, clearing his head of the last dregs of sleep, before shuffling to the cushioned chairs. Then he sits, and he waits.

He doesn’t have to wait long. Even parted from the water for over a century, he can pick up the subtle signs of another’s presence like nobody else—little flashes of color or shadow that don’t belong, slight disturbances on the surface from something rising quickly from the deep and halting even quicker.

Shouta averts his eyes and sips his coffee. He has extended his offer to speak. The ball is in the other’s court, at the moment, as Hizashi would say.

His relief when Hitoshi does surface, even if it’s just to lurk and watch him cautiously, is more palpable than he’d anticipated. But the young half-breed’s hesitance speaks volumes, leaving said relief bittersweet at best—as if Shouta’d harmed the trust between them with his scolding the night before. Not irreparably, he hopes. He doesn’t want to be like the sirens that drove the guppy away.

≈Morning. Come closer,≈ Shouta murmurs, tapping the deck with his bare foot.

Hitoshi narrows his eyes and flicks his aurals back sharply.

Yeah, Shouta’s been away from mer social customs for too long. He clicks twice in apology and then rephrases as a non-command: ≈Hitoshi, will you come closer, please?≈

Finally, the fish does approach, if only far enough to curl his clawed digits over the edge of the deck and peer up at Shouta with plain suspicion written across his scale-speckled features. ≈You’re never up this early,≈ he accuses.

≈I had plenty on my mind, and wanted a word with you.≈ He regrets his choice of words as soon as Hitoshi scowls and moves to dive, hastily adding, ≈To apologize, I mean.≈

Thankfully, the guppy stops, waiting for him to continue with those sharp purple eyes staring doubtfully back. His aurals and spines relax, as if to say, go on.

Shouta takes a deep breath over the mug warm between his palms, allowing the silence to add weight to his words. ≈I was out of line, speaking to you like that yesterday. Losing communication so suddenly, and for so long… I didn’t handle the stress well, but more importantly, I shouldn’t have turned it on you.≈

Hitoshi quietly chirrs his agreement, a scolding edge to it that Shouta might have found amusing in any other situation. What he doesn’t expect is the statement that follows it.

≈You were angrier at yourself than me,≈ Hitoshi says.

The intuitiveness of it catches Shouta off guard; it shouldn’t, because he’s spent enough time with the guppy now to know Hitoshi’s no slacker at reading people. But not only is Shouta inconsistent with which species’ body language he uses on any given day, it’s rare that he’s forward about his emotions at all. Snapping at Hitoshi was plain aggression—and here the half-breed had seen beyond that.

The anger had evolved from his uselessness, after all. An echo of the feeling gnaws at his thoughts even now. Frustration that he couldn’t help and had been forced to rely on the young one in front of him. Rage born of absence of control, desperation to protect his—

≈Well observed,≈ Shouta admits roughly, nipping his previous train of thought in the bud.

He watches Hitoshi pull himself from the water at last, but stay near the edge of the deck, tail curled down loosely into the choppy waves. It drags up another recent memory, this time of Hizashi commenting on just how mature Hitoshi is. Human memory for details must fade faster, Shouta concludes now, because when he looks at the guppy himself all he sees is a lost kid.

Sure, Hitoshi’s built like a weapon and can muster more than enough moxie to make anyone—human or mer—think twice about getting on his bad side. But he’s still a kid. Podless, exiled, clinging to a goal that will change his life, because he’s got no other options.

Shouta can’t let the air between them stay foggy. He can’t. He should’ve paid more attention to Hitoshi’s mental state last night rather than get on his tail as he had. The apology may have passed, but the damage largely remains. He wants Hitoshi to feel safe with him again, to know that Shouta can be a reliable, permanent fixture in his comfort zone.

…Oh.

Hmm.

He wants Hitoshi in his pod, he realizes in a moment of clarity. And now that the idea has presented itself, it’s fierce.

Something to bring up with Hizashi later. And all the more reason to rebuild the burned bridge. If there’s even a chance of Hitoshi accepting such an offer, Shouta needs to show the guppy that they’re on even ground regarding honesty.

It’s what leads him to admit, steadily, ≈When we lost contact… I was afraid.≈

He feels the younger siren’s eyes on him, and it takes more willpower than Shouta thought to raise his own gaze to meet it.

Hitoshi’s surprise washes away all traces of his earlier wariness, leaving his face open—and he must realize that, because a moment later he blinks quickly and glances away, clenching and unclenching his hands where they rest.

Shouta’s patient. He takes another sip of his now-lukewarm coffee and fills what would otherwise be a pressuring silence with idle noises, as if he’s not expecting a reply to that. Scratches his knee, clears his throat, casually changes his position to something more comfortable. Speak your mind, he wills the half-breed, hoping his own words sparked encouragement he couldn’t voice out loud. I’m listening.

Then, tentatively, Hitoshi murmurs, ≈…Me too.≈

Though Shouta wants to reply to that, he doesn’t. He waits.

Hitoshi curls further onto the deck, more of that long, vibrant tail of his slipping out of the water. ≈I only left his side for a few strokes,≈ the guppy explains, nerves drawing out longer hisses in his Mermish. ≈Then suddenly he thrashed like a beached shark, not talking, he couldn’t see me—≈ He cuts himself off, curling his claws into the wood of the deck. ≈He was hurting himself. I didn’t know what else to do.≈

≈You made the right call,≈ Shouta says.

The worry-line between Hitoshi’s brows relaxes, though he still doesn’t look up. ≈Yeah?≈

≈Mm. If he’d broken a bone or concussed himself, things would have ended far differently. Logically, your Song was the best option available.≈ Shouta sighs. ≈You did very well to keep him alive, all considered, guppy. ≈

When Hitoshi doesn’t quite manage to hide his pleased chirp, it’s only years of vocal disuse that stops Shouta from impulsively answering it with one of his own. It’s his turn to be caught by surprise – he cuts the budding noise off in the back of his throat with a cough. What’s he doing? By Chaos, one small realization and a few too many compliments and suddenly his instincts are trying to turn him into the guppy’s adoptive sire?

Before Hitoshi can shape the question written in his inquisitive gaze, Shouta continues a little more roughly. ≈He didn’t get upset at you Singing, did he?≈

≈No,≈ Hitoshi answers with a downwards twitch of his aurals. The outer edges of them glow faintly. ≈Not even a little bit. He, uh, thanked me.≈

Shouta’s not an idiot. It’s been downright impossible not to see the way the mismatched pair interact with one another. Over the past few weeks he’s given Hitoshi enough to consider regarding the complications of pursuing a human, especially this human. And despite Shouta’s words of warning, Hitoshi has made his decision.

It’s about time he lets the guppy know he supports it.

≈Does he know you intend to court him?≈

Hitoshi immediately and unintentionally does his best impression of Nemuri’s gaudy string lights. Shouta pretends not to notice for both of their sakes, feigning fascination with the dregs at the bottom of his mug.

The guppy gets his embarrassment and glowing under control before warbling out, ≈Not—not in quite those words.≈

≈Meaning what, exactly?≈ Shouta prompts.

≈I… told him I really like him.≈

Shouta waits for elaboration, but it doesn’t come. He bites back a sigh—and Hizashi thought he was hopeless way back when. Which, fair. Shouta is really not the siren to be teaching guppies how to court—Hizashi instigated the bulk of their early interactions until Shouta stopped denying his own feelings—but Hitoshi apparently knows what he wants already, just doesn’t know how to get it.

He pinches the bridge of his nose. ≈That’s not going to cut it.≈

Hitoshi bristles. ≈Well it’s not like I’ve ever—you tried to warn me away from him in the first place!≈

≈I was merely trying to illuminate possible consequences.≈

≈Oh, what, and now you’re all for it?≈

≈Yes,≈ Shouta replies simply. ≈Assuming it’s what you really want. Is it?≈

Seemingly rendered speechless once more, the half-breed flares.

≈Alright. Then let’s do this properly, Hitoshi. Listen up…≈

It’s almost an hour before Hizashi joins them, yawning like he means to eat the sun, with a cup of coffee tilting precariously in each hand. Behind him trails Kaminari, babbling nonstop commentary about one of the books they’d loaned him on mer culture. Despite himself, Shouta grins; he reckons his mate’s only absorbing half of the questions thrown at him at this time of day. It doesn’t stop him from nodding along eagerly to the kid’s onslaught of noise, bleary gaze unquestionably fond.

When the smaller blonde sees Hitoshi his expression lights up with relief. He gravitates to the siren as if drawn magnetically to the hand that Hitoshi has reflexively stretched out towards him.

Yeah, Shouta thinks, It’s just a matter of time.

Hizashi hands him one of the coffees, raising an eyebrow at the long-empty cup at his feet before settling in beside him on the bench.

Shouta can feel the inquiry across their bond, wordlessly asking whether the chat went well, and offers a subtle smile in response. He wraps an arm around his mate’s waist and shifts to brace his weight against Hizashi’s side. The action pulls a short laugh from the other man, which does more than any amount of body heat to warm Shouta to his bones.

He catches Hitoshi watching them—hope clear on his features—and slow-blinks his contentment. When the half-breed’s gaze returns to his own object of affections, brighter than before, Shouta considers his work done. He rests his head on the back of the bench and spends the next little while drifting in and out of sleep.

They’re down a diver today with Bakugou needed on the Shinkai Maru, so the morning passes by mostly in blessed quiet. Nemuri and Uraraka take to the water before noon, while Kaminari disappears briefly to retrieve the damaged hand-propeller so he can work on it on the deck.

Shouta returns to the waking world as mer discussions pick up again between the kid and Hizashi, to the tune of the latter’s radio reruns playing quietly in the background. The younger siren is nowhere in sight, which might explain the persistent curiosity.

Truth be told, he’s mildly impressed by the variety of questions Kaminari’s asking—everything from underwater food preparation, to the layout of the fallen community, to mer trade and currency. Through the grogginess of sleep Shouta even adds his own knowledge and memories in answer, if only because the look of wonder painted on the kid’s face eases some of the ache that comes from recall.

At one point, just after Hizashi has rattled off a list of the kinds of goods merfolk value (with no shortage of reference to Shouta’s own horde, he’s silently proud to realize), Hitoshi returns to the surface with a dead crab, one leg already dangling from the side of his mouth. Kaminari spins to him with a wide, excited grin regardless.

“I can’t wait to see your hoard, Hitoshi!” the kid announces. “Would it be okay if I added to it?”

Shit, maybe Kaminari took after Hizashi more than Shouta thought—offering up gifts already.

Hitoshi blinks, obviously caught off guard, before slowly flaring his aurals. He meets Shouta’s gaze briefly as if to ask Is it really that easy?—before looking back at Kaminari and chirping—

—just in time to see the clueless kid touch the back of his own neck with a sheepish laugh.

Oh, Chaos.

Hitoshi’s chirp jumps in pitch and he swallows the end of it, eyes blown wide.

Beside Shouta, Hizashi whispers, “That had nothing to do with me, I swear.”

Kaminari’s smile freezes; he lowers his hand. “Uh? What’s wrong?”

The crab slips from Hitoshi’s loose grip and clatters off the side of the boat. Hitoshi scrambles to dive after it.

“He’s actually hopeless,” Shouta mutters under his breath, pinching the bridge of his nose. It brings a chuckle from Yamada, who waves off Kaminari’s bewildered look. When the idiot guppy resurfaces a moment later, his cheeks and ears are painted with embarrassed light. He can’t seem to decide where to look.

Half an hour later, it happens again. The kid complains about a sore neck and pinches the knot near the top of his spine. Completely oblivious to Hitoshi, of course, who goes nearly catatonic for a moment.

The fish’s eyes dart to Shouta again, but this time alarmed instead of embarrassed.

Shouta sighs and levels an even, stony expression right back. If Hitoshi could see through any lens that wasn’t courting-brain right now he might logically conclude that the aches are from the kid hunching over the propeller with no regard for his physical wellbeing. But no. Apparently his capacity for critical thinking runs as deep as a tide pool at the moment.

Hizashi picks up on the thought and roars with laughter.

It seems that even overeager human adolescents have their limits, however. Kaminari slaps his wrench down with a loud clack and leers between the three of them, frustration written in the sharp angled knit of his brows. “Am I missing something here?”

Hizashi reins in his cackling long enough to reply, “Oh, just, maybe Hitoshi can help you work those kinks out,” which as expected earns a strangled noise from the half-breed in question.

Kaminari’s face flashes with confusion. “I know you’re teasing me, okay, but I don’t get it. What’d I do?”

He angles the question at Hitoshi for the most part, who looks ready to pass out from stress and can’t reply anyways, poor brat.

So Shouta gives him a hand. “Just show us the back of your neck, kid.”

“…What?” Kaminari huffs, then possibly realizing that Shouta isn’t one for commonly making jokes, forgoes any further protest. He shakes his head disbelievingly and turns his back on them where he sits, pushing up his hair. The stretch of his cervical spine is, as Shouta expected, completely unmarred.

Hitoshi visibly relaxes.

But it’s not enough to appease Kaminari, apparently, who spins around, and pink-cheeked, mumbles, “Well? Your turn.”

A chirr pulls from Hitoshi’s throat, low and reassuring-sounding in the face of his human’s irritation, and he fluidly eases himself up onto the deck. His bioluminescence hasn’t entirely faded, but as he slides and curls around where the kid is sitting, Shouta sees the small, relieved smile that touches Hitoshi’s face.

Instinct has Shouta initially glancing away out of respect, but in his peripherals he sees the half-breed bow his head until the rear of his neck is bared. Then the guppy’s thoracic fin fans out tall from where it juts from beneath his C7. The noon sun illuminates the translucent webbing like stained glass, vivid and unmistakably coral-fin with its array of breathtaking colors. Try as he might, not even Shouta can ignore that.

“Oh,” Kaminari says softly, sounding struck. “Th-that’s… real pretty, ‘Toshi.”

And painfully familiar. Shouta lets out the breath he’s holding when his mate’s hand squeezes his. Hizashi gets to his feet and then pulls Shouta to do the same, warmly excusing the two of them from the conversation.

Shouta catches one more look at Hitoshi as he turns to leave; the little fish has curved his body and tail around his human, now resting his head on his arms and feigning interest in set-aside screws. Despite the guppy’s neutral expression, Shouta knows he’s pleased.

Once they’re around the corner and out of earshot, Shouta lets out a short, amused huff. “Hormonal, idiotic crushes,” he grumbles.

Hizashi’s all grin and glee. “Hah! Familiar scene playing out, isn’t it? Checking his finger to see if there’s a ring.”

“Mmm.” Shouta idly strokes down his mate’s spine, thumbing aside long blonde hair. His gaze lands on Hizashi’s marked C7—his, his—and the intricate tattoo that starts below it, designed to imitate a thoracic fin. Maybe it’s the young siren’s antics rubbing off on him, but he doesn’t bother holding back his deep, purr-like trill of satisfaction at the sight.

Hizashi laughs and leans into him. “My darling hypocrite.”

Shouta presses a closed-mouth kiss to his temple, then takes a deep breath. “Do you think he realizes?” he drawls. “About just how deep he’s gotten himself?”

“Y’know, I'm honestly not sure which of them you’re referring to? But I suppose it holds the same for both.” Hizashi flashes him a sunlight smile, the kind that melts away everything else around them. “But they’ll figure it out, Shou – after all, we did.”

Chapter Text

Denki finds the first mystery gift later that day: a coral-carved jellyfish no bigger than the first phalange of his thumb. It’s a pretty thing, for all that it almost breaks after he tosses his hoodie on the end of his bed in the evening. It slips from the loose pocket but he reflexively catches it before it can hit the floor.

He resolves to ask Hitoshi about the secretive gift-giving the following day and falls asleep with a smile, stroking over the delicate bone-white curves with the pads of his fingers.

But the next unexpected present comes before he has a chance to see the siren—a long braided and beaded ribbon, presumably slipped under his door overnight, which he ties to his belt loop like an award. And when Denki heads to the ship kitchen for breakfast, he’s intercepted by one of the Midnight Boys—who nearly gives him a heart attack by brandishing a small, ornate blade inscribed with kelp patterns along its handle.

The man holds it between himself and Denki, expression entirely vacant despite the blonde’s nervous babbling. When Denki finally, hesitantly, reaches out and plucks the knife from the big guy’s grip, an invisible switch is flicked; the man blinks as if shaking off sleep, gives him one of those polite-but-still-unnerving smiles Denki’s gotten used to, and continues on his way.

Denki is both alarmed and dismayed. Until, at least, he overhears Aizawa muttering that Hitoshi has to stop Song-compelling people to be delivery vehicles. Then he gets his own ideas.

With Hitoshi diving alongside Bakugou for the morning, Denki has enough time to put a present of his own together.

He twists a bracelet from galvanized steel wire, prepped like his braces to prevent corrosion. When it looks too plain, a handful of sea glass bartered from Nemuri’s collection does the trick. These he drills holes into like the beads that decorate the mer string messages—a dozen and a half of them in varied colors that gleam brilliantly when polished.

Uraraka eagerly points him to online tutorials for beaded bracelet patterns, and even through his lunch he painstakingly braids the steel in and around the glass until even he’s impressed by the result. Sure, it has its flaws—but somehow still feels like the most important bit of metalcraft he’s ever worked.

It’s this giddy sentiment that weighs it heavy in his hands, hidden in the pouch of his sweater when Hitoshi surfaces with Bakugou that afternoon.

Denki’s still stringing his words together when Hitoshi floats closer, face bisected neatly by the calm waterline. Those lilac-on-black eyes flick to his belt; the warm pride that settles within them when they land on the braided ribbon gift makes Denki’s heart skip a beat.

He laughs and draws his fingers down it, rolling the beads under his touch. “Y’know, I thought I was supposed to be adding to your collection, not the other way around.”

Hitoshi’s lips pull into a mischievous smile beneath the water. He slips a hand above the surface, long fingers curling around Denki’s ankle; the brush of them sends nervous butterflies into flight within Denki’s chest.

“Thank you,” says Denki softly, fidgeting even as he moves to sit down. He lets his legs dangle over the edge into the water, sucking in a light breath when Hitoshi slides between his knees as if it’s the most natural thing in the world. A puzzle piece locking into place.

Ever since their quiet moments in the heart chamber far beneath the sea, things have been slightly different. In Denki’s mind, at any rate. He can’t put his finger on it, but he’s more aware than ever of their proximity and how Hitoshi… no, how both of them gravitate to one another like some great elastic has stretched between them.

It’s bewildering – could be almost frightening, if it didn’t feel so right.

The door to the below-deck snaps shut with Bakugou’s departure, grounding Denki in the present once again. He clears his throat and picks up the purple-skinned hand that has drifted up to his knee. “I’ve… I’ve got something for you too, actually.”

Hitoshi stills for a solid two seconds, fins spreading in that slow, pinned-forward way that’s both pleased and curious.

“Close your eyes,” Denki murmurs, and Hitoshi obeys.

The bracelet clinks as Denki twines its ends together around Hitoshi’s scaled wrist; he’s never seen the mer wear jewellery beyond the magical translating earring, but maybe he’d let this be an exception.

Denki swallows when he’s done, and still gently holding onto the siren’s fingers, murmurs, “Okay, y-you can look.” He counts the seconds with his too-fast heartbeat, watching the siren notice and study the gift with gradually widening eyes –

Then brightness. Hitoshi blooms into bioluminescence from cheeks to tail, lighting up the waves in pinks and purples. A breath-catching trill surges through the air. Denki is at once blinded and deafened, but in a way that feels like being buried in a hug, safe and guarded and precious.

His thoughts muddy and soften like sand under the tide. Hitoshi is Singing, he realizes, but it doesn’t have the heavy weight of orders strung through it like Denki’s familiar with. No, this is more reminiscent of a buzz from one too many drinks, lighthearted and gleeful and full of so fucking much affirmation that it brings tears unbidden to his eyes. He’s still got some semblance of control, at least – something he proves by threading his fingers through the siren’s and singing along.

He doesn’t know the words, if there even are words, so he winds up belting out the first vaguely-reminiscent pop song that comes to mind. It kinda ruins the effect, but Denki doesn’t give a shit—and judging by the crooked smile stretched across the siren’s face, neither does Hitoshi.

Eventually the high comes to an end, and the deep breath Denki takes helps his heartbeat to settle. He’s bowed over Hitoshi’s wild mess of hair with the siren’s chin resting in the crook between his knees, and when Denki’s leans back, it’s to that brilliant stare that spikes his pulse all over again.

Hitoshi lifts his head, and slowly, breathily, sounds out, “Thhhank… you.”

Denki inhales sharply; he knows Hitoshi is only repeating his words from earlier, but still, every bit of Japanese that the mer learns causes something warm and bright to bloom in Denki’s chest. He tilts his head and cards a hand through the siren’s wet locks.

“N-no problem, buddy,” he replies quietly, then laughs. “You’re getting pretty good with our words, I’m kinda jealous. How do you say it in Mermish?”

Hitoshi, face nuzzled into the inside of Denki’s knee, eases back long enough to give a response. It’s short, little more than a shush-chirp – and for once maybe not too far outside Denki’s own vocal range.

So he gives it a shot.

Which immediately draws Hitoshi’s gaze back up to his own, brows lifted and lips quirking in amusement as he flares his ear-fins approvingly.

And after that, Denki can’t imagine stopping. He asks how to say a few different things—hello, please, sorry, yes, no—with varied degrees of success in replicating the sounds. He doesn’t have expressive fins and can’t quite make up for the lack of anatomy that lets merfolk chirr and hiss without air, but the fabricated noises he makes in imitation are enough to keep the laughter dancing in Hitoshi’s eyes.

He’s not oblivious to the unhindered fondness there, either—when exactly Denki learned to read the siren like an open book he can’t say, but the smitten softness of Hitoshi’s expression steals his breath and makes his Mermish-mimicry pause. He feels the same heat in his chest and face from their time in the heart chamber, and barely resists the impulse to curl over Hitoshi again and hold him close, all to stop the merciless flood of reciprocal affection that threatens to burn him from the inside out.

Denki sighs shakily, and stretches his back to get a bit of distance, still smiling—he’s pretty sure he’s incapable of stopping right now. Then he stares out at the water with a thoughtful hum. “Ahh… what’s something else? Maybe—”

He’s interrupted, if it can even be called that, by a quiet utterance.

“Hmm?” He glances back down; Hitoshi’s eyes are closed. “What was that? What’s it mean?”

But Hitoshi just hums and turns the lower half of his face against Denki’s knee once again.

Denki grins. “Is it a curse?”

That earns him a cluck of amused disbelief and a head-shake.

“Say it again?”

The siren opens one dark eye and peers up at him, and there’s something new there now—hesitance. After a few more weighted moments of quiet, he pulls away slightly and flicks his fins back. Nervous? Maybe defensive? Denki suddenly can’t tell.

Still, Hitoshi repeats the phrase—it’s too long to be a single word—a bit more clearly, offering a small smile afterwards when Denki clearly doesn’t understand.

But then, as with every other bit of Mermish that Hitoshi has given him, Denki tries it out himself—and makes it through not even half of the whispery sounds before Hitoshi cuts him off with wild, frazzled protest. The siren’s cheeks are flush with light again. It’s unbearably endearing.

Denki grins again. “You can’t offer an option and expect me not to try it,” he points out quietly, hearing the door to the below-deck open somewhere behind him. “I’m still in the dark here, ‘Toshi, if only you could just tell me—oh! Professor Yamada! Professor, what does, uh, ‘sh—”

Half-turned to where the blonde man has emerged, Denki doesn’t see the purple hand until it’s securely over his mouth and pulling him down. A bit more forceful than necessary, because it knocks Denki’s breath out when his back hits the deck.

Then Denki registers Hitoshi’s wide eyes and bristling hair and fins, and as soon as air makes it back into his lungs he’s howling with laughter at the siren’s mortified expression.

He rolls onto his stomach; they’re at eye-level now. “Y-you sure it’s not a curse?” he asks, blinking back tears through his giggles when Yamada passes by and Hitoshi’s hair finally settles. It’s decidedly pufferfish-like. “No. Okay. Just private, then?”

The affirming aural flare is sharp and fast, and Hitoshi’s gaze averts once more with an embarrassed scowl. Clearly wasn’t expecting Denki to get hooked on the mystery translation. Ha. He’d learn.

Denki smirks. “Ooh, a compliment?”

Another pause of hesitation, and Hitoshi shrugs. Then flares again, much more slowly.

A compliment. Maybe it’s silly, especially because Denki already knows that Hitoshi likes him, but hearing him put it into words—sort of—lifts his heart into the goddamn stratosphere. He rests his chin on his folded arms, almost nose-to-nose with the siren.

“Well, you’re not bad yourself, boo,” he manages with a cheeky smile before Hitoshi splashes him good-naturedly and he’s forced to roll over to escape. His shirt and hair are drenched by the time he’s back upright, but his ribcage feels as if it’s been filled with bubbles, and Hitoshi’s grinning once again.

The carefree hours can’t last forever, though, and with a sigh, Denki checks the time on his phone. It’s already well into the afternoon.

“I gotta finish up some work inside—I kinda put it off this morning, y’know?” Not that he regrets any amount of time poured into the shining bracelet on Hitoshi’s wrist, but Bakugou will have his head if he procrastinates for too long.

Hitoshi sinks back a few feet away from the edge, wearing a strange expression.

Denki reads it as disappointment, because that would make sense, and gets to his feet with the help of his cane. He’d come out with his wheelchair just in case—the aches from two days prior were going to stick around for a while yet—but he could manage for now. “Yeah, it’s not super fun, but I gotta pay for that future houseboat somehow! It’ll be the last of my tasks for the week. I want to get it done before…” He waves a hand idly at the water.

He still doesn’t really understand what the ley-line is about to do, what the whole ‘waking up’ thing actually entails. None of them seem to know for certain; Denki’s sure Aizawa has some inkling, but he’s kept quiet about it so far. Either way, they’re six days deep into the week-long timeline Hitoshi’d given on his return. Denki wants to be as ready as possible.

He stretches out the kinks in his spine. “I’ll be back in a few hours, promise.”

But then, as he’s about to turn away, Hitoshi surges onto the deck and pulls himself determinedly towards Denki’s half-folded wheelchair. It isn’t until the siren literally wrangles his way into it with an uncomfortable grimace that Denki understands what’s going on.

“You—you want to come in,” he blurts, not entirely a question.

Hitoshi doesn’t fit in the chair by any sense of the word; he can’t properly sit back against it without compromising his lumbar fin. His tail, which alone is longer than Denki is tall, spills boldly from the seat and writhes against the deck as he struggles to get comfortable. Still, he meets Denki’s baffled gaze with a determined one of his own, and flares his aurals.

Denki has never even considered Hitoshi coming inside as a possibility. As he watches, the dripping siren winces and sucks in a sharp breath, readjusting once again to using his lungs—then taps the armrests of the chair expectantly.

And so Denki laughs and runs his hands through his hair. Alright. Okay. They’re doing this.

It takes a minute to work out the logistics of it; Hitoshi’s tail is too long and not quite flexible enough to lift completely out of the way, so it makes the most sense to wheel the chair backwards, pulling it along behind him instead of pushing. He snags some of the swim towels from a nearby rack and wraps them around the end of the siren’s tail so it doesn’t chafe when dragging along the deck.

It’s surprisingly easy to get Hitoshi inside. Then, of course, the intended workload is left to wait a bit longer: he can’t pass up the chance to give his overgrown fish a tour of the Midnight Lady.

Eventually they stumble across Aizawa curled up in a monstrous yellow sleeping bag in Nemuri’s repurposed party-lounge-turned-planning-suite. He takes one long, hard look at the pair of them before rolling over with a muttered, “Don’t stay out of the water too long.”

Speaking from experience, probably.

So with that they finally head to Denki’s borrowed room; it’s where he has his notebooks and textbooks and the small laptop that he doesn’t dare bring deck-side. As he wheels Hitoshi in, he’s suddenly more conscious than ever of the little knick-knacks and belongings strung across the desk and bedside table, spilling in places onto the floor. But the siren’s gaze is entirely curious, no hint of judgment, and that fuels Denki to show off a few of them.

He’s not ready for Hitoshi to literally pull himself off the chair and onto the (unmade) bed, but that happens anyways, and then the fish has the gall to give him a strange look—as if it’s in no way his fault that Denki’s flushed pink and stammering all over again.

Denki does need to get work done, however, so despite the chest-fluttering distraction of Hitoshi literally nuzzling his pillows and pulling the sheets into some strange semblance of a nest, he takes a seat and opens his laptop. At least his tasks don’t require a high degree of brainpower today – not sure he could manage it with the way the siren keeps fiddling inquisitively with everything he picks up. Denki’s cellphone. A nearby engineering textbook. A small Pikachu charm that had fallen off his keys. The shirt Denki had worn the day before, discarded at the end of the bed – which Hitoshi sticks his head through before thankfully coming to the conclusion that it’s a few sizes too small to squeeze into the rest of the way.

The curiosity fades away over the course of the next two hours, until Hitoshi’s seemingly satisfied with this new land-bound environment and content to lay among his assembly of sheets quietly. Denki feels the siren’s eyes on him as he fills the silence with stream-of-consciousness mumbled explanations for the problem he’s working through.

When Denki finally finishes and glances over, his breath catches at the warmth in Hitoshi’s eyes. The siren’s lips are pulled into a small but fond smile, partially hidden by the pillow he’s resting on.

“Looking real comfy,” Denki says around the curl of giddiness making his chest feel as light as air.

Hitoshi makes a sound of agreement and rolls face-down as he stretches; his thoracic fin spreads as it had the day before, albeit this time with no sunlight to catch it. And, like before, Denki has to consciously resist the urge to reach out and touch it like he feels inexplicably compelled to. Clearly it means something important to the mer, and he’s not keen on overstepping bounds, no matter how close he’d like them to be.

It doesn’t escape his attention, however, that Hitoshi’s hues are more faded than earlier—less vibrant around his gills and fins and other delicate, non-scaled areas. Aizawa’s earlier warning comes to mind.

“I guess we should get you back in the sea,” he sighs, prompting another long, unreadable look from Hitoshi before the siren both flares and nods his agreement.

The trip back to the deck is quiet but comfortable. When Hitoshi slips back in the water, he makes a low sound of relief; Denki notices that his color returns almost immediately. While Denki’s relieved, the change is also telling of just what restrictions lie between them, that neither can exist safely in the other’s world for a notable amount of time.

I still want him, though.

Denki’s ready to say his goodbyes for the night, but Hitoshi indicates for him to wait, and dives away.

He’s been waiting for five minutes when another set of footfalls shake him from his conflicting pining; instead of moving past, they pause, then draw closer. Denki glances up when Yamada lowers himself to the edge of the deck beside him, offering a questioning smile as greeting.

“Everything alright, little listener?” the man asks, uncharacteristically soft for once.

Maybe it’s the fact that there’s been nobody else to discuss it with comfortably, or just the fact that of everyone, Yamada would be best able to relate—but Denki can’t keep it buried anymore.

“I think I want to be with him,” he admits with a self-conscious laugh. “Like. With him. M-mated?” He chews his lower lip for a moment, taking the man’s patient silence and slow nod as encouragement to continue. “Will having a bond… change us? How—how did you and Mr. Aizawa make it work?”

Yamada’s expression falls into something melancholy. “The circumstances are… different, kiddo. Shouta was already trying to distance himself from the sea out of guilt. But even without that, our family bonding—and then mate bonding—helped us understand each others’ wants better. It does change you, but not, I believe, in the way you’re imagining.” He taps Denki’s temple twice with his pointer finger, wearing an understanding smile once more. “It helped us adapt despite our differences. Not dissimilar to your experience down in the Heart.”

“You could understand each other?” Denki asks, eyes rounding.

“In a sense, yes!” A grin splits across Yamada’s face and he turns to look out at the water. “I misunderstood so many of his courting efforts until then, would you believe it? And my flirting went right over his head. It wasn’t until the bond that we recognized that in hindsight. He rarely exhibited courting behaviour to begin with—but once we could feel each others thoughts and intentions?” The laugh that follows echoes into the evening. “A bond is really something special, Kaminari. It’s a blessing.”

There’s something about the professor’s openness and enthusiasm that’s infectious, and the uncertainty plaguing Denki’s thoughts recedes in favor of curiosity. He slips off his sandals and submerges his legs to mid-calf. Despite the chill, it’s oddly relaxing.

Then he leans back on his palms. “Courting? Like…”

Yamada’s grin widens, if at all possible, flashing perfectly straight teeth. “Have you been given any gifts lately? Noted possessive behaviour even when the two of you are alone?”

Denki flushes. There’s no denying either of those–and he’d given the siren a bracelet in return–

Hitoshi has been courting him. It sends a nervous, excited thrill down Denki’s spine. Hitoshi wants him back.

The feeling bubbles out in a series of strangled laughs, and he scratches the back of his neck sheepishly, aware that Yamada’s eyes follow the action. “I—well—yes to both,” he admits. “Wow. That’s—cool! Yep. Cool cool cool. I had a feeling, but like, not sure, yanno? Wow.” He takes a breath and releases it to steady himself. “Right. So… what should I do? You said yourself that Mr. Aizawa was already trying to leave the sea, but—Hitoshi’s not, right? I can’t ask him to do that.”

Yamada hums, and releases a long sigh. “There isn’t much advice I can give in that regard, kiddo. Just… follow your heart, yeah? Mer are intuitive; they’re more in-tune with the ebb and flow of fate than humans will ever be.”

Then he claps Denki twice on the shoulder, gets to his feet, and makes his way back inside.

The evening is chilly. It’s nearly sunset, and yet already he Denki can see the stars shining bright through the pink-purple sky. One of those nights that the city back home would never see, the light and noise pollution of his old block far too potent to enjoy the majesty that lie beyond. Here on the ocean the rest of the world falls away.

He waits another ten minutes before some instinct he can’t name makes him glance down at the waves, and a moment later, Hitoshi breaks the surface, scattering the reflection of the sky into thousands of rippling shards. He’s beautiful. He’s smiling.

If this is what ‘following his heart’ means, Denki’s sure he could stay right here forever.

Hitoshi swims up along the boat again, until he’s between Denki’s legs where they dangle over the side. In the mer’s grasp is a woven hoop as broad as his spread hand, with a series of other long knotted and decorated strings trailing in the water below. A message – but far fancier than most Denki has seen. It’s on par with the ones in Aizawa and Yamada’s room on the Shinkai Maru, and although he can’t read it yet, Denki knows without a doubt that it’s another matter of courting.

Hitoshi lifts the message out of the water and gently sets it on Denki’s thigh.

Denki’s heart sits in his throat, and the same desire that he’s been faced with countless times over the last few days slams him again with a vengeance, except—this time he’s sure.

“Hitoshi, can I—can I kiss you?”

It’s a testament to how much Denki wants it when he doesn’t immediately backtrack at the slight puzzlement on the siren’s face. Hitoshi drifts between his knees, silent for a moment, before quietly repeating “Kiss,” under his breath. No recognition of the word at all; complete unfamiliarity.

Oh boy.

Denki can feel the blood rushing to his cheeks. “Ah… it’s. It’s a thing humans do when—they have, uhh, feelings, like—” he ghosts his fingers along the string message, almost reverently— “the um, courting kind of feelings?” He can’t look away from Hitoshi, not when the siren is staring back at him so intensely, some markings picking up a glow. “It’s nothing complicated, you just. Just uh.”

He reaches out slowly to cradle Hitoshi’s cheek with one palm, brushing his thumb over the siren’s dark lower lip. It’s cool, but soft.

Denki swallows. “C-can I show you?”

Hitoshi barely moves an inch apart from his fins flaring, the bloom across his cheeks radiant.

He’s so ridiculously pretty, Denki thinks as he leans in and closes his eyes, coaxing Hitoshi with a hand to meet him halfway.

The first touch is gentle, questioning—keeping it chaste. Hitoshi has always run cool-to-cold as a consequence of biology, but it’s not as jarring as Denki had imagined. The mer’s lips are smooth and pliant beneath his, carefully closed, and the magic that pulses through him is so close Denki can practically taste it. He presses closer, tilting his head, letting out a pleased sigh because he’s waited so long and his wayward daydreams have nothing on this.

Hitoshi’s low, throaty chirr in response yanks him back to reality.

Oh gods, that sound. Denki pulls away, pulse hammering, swiping a tongue over his lower lip and tasting salt. “See, it’s simple—”

His breathy utterance is interrupted by Hitoshi reclaiming his mouth again, instead rolling into a broken little noise of surprise, because wow. The siren plants his palms on either side of Denki’s thighs and gradually rises into his space until Denki almost has to tilt his head up to keep the kiss from breaking.

He tentatively threads fingers through Hitoshi’s damp and wild hair. His other hand braces back against the deck, giving Hitoshi more room to lean—which brings them nearly chest to chest as the siren breaches the space in a heartbeat. The physical thrum of Hitoshi’s trill rumbles like a guttural purr between them, and Denki goddamn melts, giving in to a deeper kiss and running his tongue tentatively along Hitoshi’s lower lip until his part, too.

Maybe moderate-brained Denki would continue to have second thoughts about delving further, but current Denki does not, dipping until he can test the sharp points against his soft skin. The quiet chirp Hitoshi offers is as sweet as it is fascinating, because he can feel it—and Denki downright shivers when the siren catches his tongue delicately between his incisors.

But even Hitoshi is relying on lungs now, and when they part again, they’re both hungry for air. Denki’s tongue tingles faintly. Gonna need to explore that more later, he thinks, laughing breathlessly into the short distance between them, unable to find words for the way his heart flips at Hitoshi’s answering grin.

The siren leans back in, but this time it’s to nuzzle Denki’s cheek and temple momentarily before dipping their foreheads together, sending wave upon wave of affection spiraling through their temporary bond—

The door to the cabins opens.

“Kaminari?” Uraraka calls out. “Bakugou says if you don’t come get dinner soon he’s tossing it overboard to your fish!!”

Hitoshi’s flash of good-natured resignation directly mirrors his own.

“Keep him busy a minute longer, will ya?” Denki calls back with a groan, then feeling Hitoshi’s curiosity at the contents of a possible free meal—ravenous fucker that he is—adds, scowling, “I’ll be there soon.”

Hitoshi rumbles with amusement, sneaking in a final chaste peck as he sinks back down to the water. Must approve of kissing, and he’s a fast learner, which is great because Denki foresees no shortage of it in their near (and hopefully ongoing) future.

He watches, spellbound, as Hitoshi circles about in the water a few meters off—and like the flick of a switch blooms back into a full bioluminescent display. Light catches on the wires and glass of the bracelet on his wrist, which he brings near his face as he murmurs what Denki now recognizes as Thank you.

At the sight, Denki can barely summon enough air to breathe let alone talk, so he just smiles and touches his fingers to his mouth.

He’s so hopelessly enamored it hurts.

When Denki finally makes it to the dining room, Yamada eyes him curiously for just a moment, vibrant gaze alight.

Then, as an impossibly wide grin splits across his face, says a bit too loudly to be purely conversational: “Hey Nem, Kaminari’s looking a bit warm, don’t you think?”

The ex-siren gives up her lobster tail with a scowl.

Chapter Text

They’re sitting down to a late breakfast on the deck when it happens.

Something crackles suddenly and vibrantly inside Denki in a way that makes him pause with his spoon halfway to his mouth, and in the next instant, his surroundings explode into noise.

There’s a loud crash in the kitchen cabin at the same time that Nemuri leaps to her feet with a resounding, delighted trill; Yamada staggers up as well, holding a hand to his temple and clearly reeling, just in time to meet his husband at the doorway. 

“It woke up?” Yamada asks, voice shaking slightly. “Just now?”

Aizawa is wild-eyed and looking younger than Denki’s ever seen him, all traces of his seemingly-chronic exhaustion lifted in this moment. He chirps in an overwhelmed Hitoshi-like way—it’s strange to hear, with how rarely he vocalizes Mermish, and stranger still when he breaks into a quiet, low trill and pulls Yamada into a fierce hug in lieu of finding words.

Denki looks to Hitoshi, just in time to see him splash over the side.

“Hitoshi—” he calls out, concerned, only to be squawk when he’s swept up into a brief hug of his own by Nemuri—who now has tear-streaked cheeks.

“Shhh, shhh, let him go, he’s fine, he’s perfect, this is what we’re all here for, sweetie!” she warbles wetly into his hair. Thankfully she releases him a moment later to grab Uraraka instead and spin her around on her feet (after narrowly missing Bakugou, who had the sense to dodge). “Can you feel her?”

Denki reaches for that sixth sense within him again, stemming from the link to the ley-line he’d made at the deep-sea heart. Whereas before it had been subtle, a ripple in a tide pool, now the intensity pulses and pulls like a wave, slow and steady like a heartbeat at rest. “It’s really alive again,” he murmurs in wonder, letting the sensation wash through him. 

“She is,” Nemuri coos, leaning over the side now, skirting her fingers adoringly along the surface.

“Who?”

“A new royal.” It’s Aizawa who answers this time, in a voice that sounds like it’s been dragged over hot coals. Denki glances back at him and it’s—it’s jarring. His usual composure has fractured into something equal parts devastated and hopeful, and Denki swears the man’s shaking like an addict in withdrawal, leaning bodily away from his husband towards the railing of the boat. There’s something in his gaze that’s all wrong.

Yamada tries to shift them to block the view, to no avail; Denki realizes that professor’s wide grin is more akin to a grimace. “Shou, please,” he says calmly, but it’s got enough quiet strain that it pings Denki’s alarm bells. 

And not only his, it seems. Bakugou gets to his feet and stands between the pair and the side of the boat, arms crossed; Uraraka hovers beside him wearing a concerned frown. 

Aizawa appears to stare right through them. “A royal,” he repeats breathlessly. “Feels just like—I have to make sure—I need to go.”

Yamada tucks his face into his husband’s neck, arms tightening around him, grip white-knuckled. “Shh, Shou, it’s not him—”

“I need to go— ” and he lurches towards the water.

Despite being the taller of the pair, Yamada might as well be made of straw for all the good his efforts to hold Aizawa back do. Bakugou’s there in an instant to help, but even with the two of them he’s gaining ground towards the side of the boat, staring into the sea like he needs it to live. 

It’s only when Nemuri collides with the group a few feet from disaster and adds her own superhuman strength that they collectively wrangle the man to the deck floor. “Come back to yourself, Shouta,” she hisses. “You’re better than this. It’s not him. ”

Aizawa thrashes.

“Put him under,” Yamada says weakly, and Nemuri nods.

“Is he okay?” Uraraka asks hesitantly, echoing Denki’s line of thinking. “What’s happening to him?”

At first it seems like they won’t get a reply. Nemuri’s busy incanting, some sort of sleeping spell judging by the pink mist that gathers at Aizawa’s mouth and nose and makes his body slowly fall slack. 

Yamada takes a deep breath before looking up at them with a wobbly, pieced-together smile that couldn’t fool an infant. 

“He’s just hearing the magic’s call a bit louder than the rest of us, kiddo.” Yamada brushes long fingers over his husband’s tangled mane, as if handling a child rather than the strongest, sturdiest being aboard the ship. “It brings back memories that… hurt, a bit. But he’ll be fine.”

It takes a combined effort to get him below-deck, where Nemuri bundles them all up in heavy blankets. Yamada queues up old reruns from his radio show and settles in with Aizawa’s head on his lap, finger-combing through his husband’s hair. The ex-mer doesn’t stay unconscious long, but when he does come around, it’s with a heavy sigh and a whispered, “I’m sorry.”

Denki gives them privacy, focusing on the soft music. He can’t recall listening to this particular rerun before, especially not with the slow, downtempo songs that are playing. There’s something soothing and familiar to them that he can’t put his finger on. Despite the unspoken tension in the room, he finds himself drifting.

Must have fallen asleep, too, because he wakes with a start at the sound of Bakugou thundering down the stairs and an urgently uttered, “They’re here! ”

Denki’s the last to make it to the deck, of course, but that does nothing to put a damper on the relief that hits him upon seeing Hitoshi back aboard. The wind has picked up in the hours since his departure, whipping at their hair and disrupting voices, but even it can’t carry away the low, satisfied trill that Hitoshi lets out when their eyes meet.

“Denki, here, ” the mer says, shifting carefully.

Then Denki’s gaze slides downwards to the figure tucked against his side.

A mer child.

She’s pearl-white, skin and scales both, flecked with patches of silver and pastel blue. Four, maybe five years old if she was human, except she’s clearly anything but . Her hair drifts around her shoulders near-weightlessly, seemingly unaffected by the wind. Where the sunlight hits her scales, she positively glows.

Denki watches Aizawa get to his knees, reaching out.

For a moment something too-sharp and possessive flashes across Hitoshi’s features, a quick raise of his lip and flick of his fins—but it passes as quickly as it had come on. With a whisper-chirp he gently eases the sleeping child into the other’s hold. 

Aizawa receives her with bated breath. The strange youthful awe from earlier returns in an instant, making itself known in the brightness of his eyes and the quiet chirr he releases once she’s safely cradled against his shirt. She’s fast asleep—already using her lungs, Denki notes, seeing the soft rise and fall of her chest—and doesn’t stir in the slightest when Aizawa curves down and presses his forehead against hers.

“Eri,” he whispers reverently a moment later.

Yamada crouches down at his side, wrapping an arm around Aizawa’s shoulders. “That’s her name?” he asks, to which Hitoshi chirps and flares in confirmation. A blinding smile lights up Yamada’s face. “Little Eri, huh? Well then! Welcome to the world, Your Highness.”

And as if the words herald the true start of celebration, Nemuri gives a loud whoop that peters off into trilling, soon joined by a chorus of echoed welcomes and cheers. Uraraka throws her arms around Hitoshi and offers eager congratulations; even Bakugou is grinning as he mutters sourly that they’ll wake up the kid. But despite their noise, she sleeps on.

Denki’s so caught up in his own unexpected laughter that he jumps when Hitoshi’s arms circle his waist. The siren’s cool mouth presses against the back of his neck, quickly warming with the contact. He leans back into the touch and tries to ignore the curious looks that several of his companions shoot him, ruffling the siren’s wild purple hair with a chuckle.

“C’mon, my dude,” he says under his breath, feeling his face heat up when Hitoshi continues to nuzzle the spot with almost feverish interest. “Don’t want Bakubro getting on my ass about PDA already , and like, with the old folks around it’s kinda especially—” Denki pulls forward suddenly with a yelp, because maybe he’s crazy but that sure felt like a glide of teeth over his skin right then. 

Hitoshi clicks twice in apology, slurring it into a trill that feels oddly sloppy compared to his usual. It’s no wonder; to Denki’s mental touch he feels almost drunk with hope and desperation, barely able to string any emotional clarity together for more than a heartbeat before returning to an insistent sense of together, together. It’s only a handful of seconds before he’s back at the base of Denki’s neck, mouth moving insistently against that same spot.

And, despite how much he really likes kissing the silly fish, Denki’s gut swoops uncomfortably. There’s something different happening here that he plainly doesn’t understand – and so he wriggles free of the arms around him with a sharp “ Hitoshi, ” spinning on the spot.

The question ready on his tongue dies at the look the siren wears, caught halfway between a high and confusion, the scales across his cheeks and forehead lit in blush. Hitoshi chirps softly and for once Denki’s not sure what to make of it in the slightest – they stare at one another for a heavy moment of silence where he’s certain Hitoshi is trying to say something , but for the life of him Denki can’t parse it.

They’re interrupted by a pair of shadows coming to loom over them.

“Hitoshi, go help Nem fill the deck tub with seawater,” Aizawa says slowly, indicating towards the Jacuzzi they’d been draining over the course of the last few days. His tone is firm but gentle, perhaps due to the sleeping child still curled up against his chest.

Hitoshi’s fins flick back as if to protest, but he slides away with a discouraged click. 

And they’re left with a silence that Denki can’t help but immediately cut into. “I don’t—I’m fine, I overreacted. I wasn’t sure what he was doing.” 

Yamada folds down to his level with a grunt and a sigh, sitting cross-legged beside him before offering a melancholy smile. “It’s alright, Kaminari. Do you recall a few days ago, the whole debacle with showing him the back of your neck? Pretty weird at the time, yeah?” He waits for Denki to nod, and nods slowly himself. “Well! You see, on merfolk it marks the top of the thoracic fin – the C7 vertebrae – and is said to link directly to their magic.”

Denki swallows dryly. “But… I’m human.” 

The professor bobs his head. “Right, but that’s not what I’m getting at, exactly – just that it’s culturally a very, er, loaded place on the body for several reasons based on that premise. Namely for forming bonds. Of both the mate and podmate varieties. You get me?”

Before Denki can reply, Aizawa hums, lowering himself into a nearby seat. He brushes Eri’s long white curls to the side, displaying the small, folded thoracic fin. “…Baring it as he did to you then is a sign of deep trust and protectiveness and confidence. It’s… the point of highest vulnerability.” He covers the child’s with a cupped hand. “From a pod standpoint, touching or allowing others to touch the fin is a way to calm each other down or show affection.”

Rubbing his cheek, Denki murmurs, “So I just unintentionally rebuked a nice gesture.”

“Not exactly,” Yamada continues. “What he was doing… that’s more of a bid for a life mate. A siren’s mouth holds their best natural weapons and the focus for their strongest magic. To bite the base of the fin, over that vertebrae, is the traditional way of sealing a life mating bond. Tying the pair together through their magic, if you’re following along.”

“He wouldn’t do anything without your consent,” Aizawa cuts in, perhaps reading the shock on Denki’s face. “That wouldn’t actually work.”

Denki’s lost for words for a moment, then laughs, high and awkward. “I feel like I’m getting The Talk from my parents, except like, with more magic involved,” he admits, which earns him a full laugh from one of the men and an amused eye-roll from the other. But at the very least it does he job he’d planned for it and breaks the tension; gives him a bit more room to think. “So it’s… a part of courting, okay. I can handle knowing that. Just happening a bit quicker than expected.”

His doesn’t miss the look that Aizawa and Yamada share.

“Eri’s influence has a hold on him,” Aizawa mutters. “Like a shot of hard alcohol going directly to born instincts. He’s feeling invincible right about now. And trying to form bonds in the only way he think he’s allowed. Without a pod – a family group – that’s you.”

“Oh,” Denki murmurs, blowing out a breath. “I’m…”

“Not ready,” Yamada finishes for him. “We know. Which is why…” the two of them share another look, and Denki can’t help but feel like they’re only talking out loud for his sake. “Shou, it’s a good time.”

Aizawa strokes Eri’s hair, then nods, and hands her to his mate. Finally, he gets up and pads over to the Jacuzzi, now half-filled in preparation for Eri’s—and likely Hitoshi’s—comfort. 

The latter has already taken up residence within. Hitoshi’s gaze first snaps to the approach before darting past to Denki and Eri in turn. Despite Denki’s reassuring smile, the young siren looks uneasy, perhaps even cowed, shifting to make room when Aizawa hesitantly tests the water, grimaces, and slides down in beside him. 

Denki holds his questions back at first, listening to the low, rumbled shushing and clicking of Aizawa’s Mermish. But when Hitoshi slaps the surface with a fin, frustrated, he opens his mouth to ask.

Yamada beats him to it. “Shou’s explaining why a mate bond might not be appropriate for you right now,” the researcher says, settling a hand on Denki’s shoulder. They’re both quiet as they listen to Hitoshi’s sharper response, to which Yamada hums before translating. “He says that he doesn’t care if you’re human and not used to pods, he himself is an odd one out too, and it feels right! And—” 

There’s another pause for Aizawa’s reply, slow and drawn-out, and Yamada smiles.

Before Denki can question it, there’s an echo of shock down the mental link between he and Hitoshi – only a moment before the fish throws himself at Aizawa and knocks him sideways in the makeshift pool.

“Hitoshi!” Denki starts, lurching towards the Jacuzzi, but Yamada’s grip tightens and the man lets out a short, amused reassurance. 

Aizawa resurfaces, spitting out water but grinning; his hand goes to Hitoshi’s flared thoracic fin as the mer wraps around him like an overexcited eel. Hitoshi in turn wastes no time shredding the back of Aizawa’s shirt, under which Denki notices a dark patch of scales and some slightly-raised plates jutting forth along the line of his spine in the same spot.

Denki flounders for an explanation, watching the siren hang on to his land-bound counterpart in an overly intense hug. Perhaps it’s a trick of the light, but the air around the pair seems to shimmer. He turns to Yamada, but to his surprise the man is pulling off his own jacket.

Still, he manages to catch that vibrant green gaze, and Yamada gives a full, toothy smile. “Shou just welcomed him to the family,” he explains.

Their ‘pod’, Denki realizes, turning back to the two in the pool with new understanding, and also a healthy dose of hesitation. Seeing the two typically-standoffish individuals dropping those walls in a way he hadn’t expected, the whole thing seems uncomfortably intimate to him.

He says as much, quietly, for only Yamada to hear.

“Try to stop thinking like a human for a little while, kiddo,” is all Yamada offers in reply, tossing his shirt onto a nearby lounger and stepping down into the pool with a wince at the cold. Almost immediately, Hitoshi unlatches from Aizawa to switch targets, reaching for the back of Yamada’s neck as well, where an intricate tattoo with an abstract oceanic design lights up softly in response.

Aizawa isn’t looking at Hitoshi like he would his husband, of course; the slanted smile and quirked brow strike more of a parental presence. But Hitoshi, with the family bonds fresh and settling, turns his own gaze to Denki. The longing and question there is clear now, and try as he might to follow Yamada’s advice, Denki can’t help but feel spooked.

He forces a smile and a thumbs-up, then excuses himself to the couches. 

It’s not long before someone approaches—but to his surprise, it’s Aizawa. The man’s skin is mottling towards charcoal and scales from the water’s touch, which Denki probably should have expected, but it’s still a shock to see. He settles down in the seat beside Denki, and sighs, bracing his elbows on his knees and his chin on his knuckles, staring out over the water.

“Are you having second thoughts about Hitoshi?” he asks.

It’s so far from what Denki’s expecting that he physically balks, turning to face the man so fast that he nearly gives himself whiplash. 

“No!” he practically squeaks. “Never. But the magic, I’m not… it’s…” He trails off, unsure of how to explain. How could he explain, when the man beside him had his whole colony destroyed by people seeking the very power that Denki himself once sought – and paid the price for?

He expects a new question, but Aizawa waits for him to find his words, instead. So he does just that, anxiously bending and cracking his fingers as the reply arranges itself on his tongue. “It’s just… something so permanent . What if he changes his mind?”

“He won’t. None of us will,” replies Aizawa without a hint of doubt. 

None of us. Right. Denki swallows. It’s not just Hitoshi , after all; from what he’s gathered from reading Yamada’s studies and interacting with the adult pair, the pod bond connects them all in some way. Was that… too much to ask of them? Shouldering his way into their newfound bond with Hitoshi, making waves in a pool that’s still churning? 

Maybe he’s been silent for too long thinking on it, because Aizawa putting a hand on his shoulder briefly makes him jump. His instinctual apology dies under the peculiar weight of the ex-siren’s gaze, and this time it’s almost as if Aizawa is the one fighting for the right words.

Finally, the man looks away again, and speaks. “You’ve… shown more compassion for the mer than anyone I know, save Hizashi.” He rubs his jaw. “We could do far worse than bringing you into the pod.”

“What the old grump means, ” Yamada interrupts with a chuckle, approaching to sit on his other side, “is that we can’t do any better , and we’ve been thinking of offering for a while now.”

Denki squirms. “E-even the expedition ends? The bonds… they’re long term.”

Yamada wraps an arm over his shoulders. “As long as it gets, Kaminari,” he says with a smile. “You mentioned that nobody was waiting for you, yeah? Wouldn’t it be nice if someone… or two someones… were?”

It takes a second to sink in, then rocks Denki. He whips his gaze between the two of them.

Aizawa gives his husband a dry look before clarifying. “We have property on Chichijima. Our home’s open to you, whether you take the bond or not. But.” He scratches at his scruff with a sigh. “We hope you will. Take it, I mean.”

Yamada gives him a gentle, one-armed squeeze. “You’re already as good as family to us.”

Avoiding the wetness that comes to his eyes would be a fruitless endeavor, Denki knows, and he can’t hold back the sniffles as his body fills with warmth at those words. He hears Aizawa make a horrified grunt and it’s enough to tear a laugh out of him—one closely mirrored by Yamada on his other side, who only hugs him tighter.

“Thank you,” he manages after a minute. “R-really. These last few weeks have b-been everything to me. I just don’t want to let any of you down. Especially…” he tilts his head towards where Hitoshi is cradling Eri in the makeshift pool, chatting with Nemuri, and thankfully distracted enough not to notice Denki’s moment of weakness.

“I don’t think you need to worry about that,” Aizawa mumbles, sounding amused. He reclines in the seat, draping his arms along the back and giving the purple mer across the deck a long, thoughtful look. “Damn guppy’s willing to bet everything on you.”

Denki follows his gaze. “How can you tell? From the bond?”

“Oh, kiddo, it’s more obvious than that, ” Yamada coos, and at Denki’s blank look laughs again and ruffles a hand through his hair. “He brought the hope of his entire species straight back to you, didn’t he?”

Denki opens his mouth to protest.

Then closes it.

Because Yamada isn’t wrong.

It’s still fresh in his mind, after all. ‘Denki, here, ’ his brilliant, beautiful mer had said, the first moment they’d seen each other after Eri was retrieved. Lavender gaze and whispered invitation only for him – even nearly growling at Aizawa as a first defensive instinct.

He gets to his feet and moves towards the pool, dissociating, feeling as if he’s floating on a cloud. 

Hitoshi takes one look at him and hands Eri over to Nemuri, who winks and glides away. But the siren doesn’t have eyes for either of the girls right now – no, he’s trained entirely on one approaching individual at the moment, gaze soft and searching. He chirrs softly, then, “Denki?” 

The lightness of his heart shapes the form of his words. “If you’ll have me,” Denki says quietly, voice shaking. Hitoshi watches him with unbridled intensity, lips soundlessly, questioningly shaping the words back. Denki swallows. “If I’m enough …” 

He doesn’t need to finish the rest of it. Hitoshi’s pupils blow wide and his fins erupt with light; their hazy link surges with affection. He’s pulled into the pool in an instant, but mindfully so, Hitoshi carefully arranging Denki across his lap and bringing their heads together.

A flood of happiness and eagerness and hope washes through Denki, not unlike the feeling of Eri’s emergence only hours prior—but this was all Hitoshi , here and now and insurmountable, pulling him under into some other space between their minds, until the boat and sky beneath and above seem to disappear altogether. 

There’s a cool hand tracing over the base of his neck, and he mimics it, touching the soft webbing of Hitoshi’s thoracic fin with gentle, curious fingers. It flutters and flexes under his hold, and when he feels the strange sensation of tingling in his fingers and on his back, he dares to hope. Maybe him having lost his affinity wouldn’t matter after all; maybe the strange prickling, thrumming heat can make up the difference—

But as it continues to burn, it burns colder, in his chest, in his lungs, deeper , the flood of Hitoshi’s magic reaching and searching for something—

Anything —

And finding nothing at all. 

When he next opens his eyes, it’s to the sight of the ceiling of his bunk onboard the Midnight Lady . He traces the swirls on the ceiling with his gaze, shaking off the remnants of dizziness, fully aware of Aizawa in a chair beside his bed.

He doesn’t have to reach far to know what happened.

“It didn’t work,” he says, voice frayed and cracking.

“No,” Aizawa agrees, “it didn’t. But you thought it wouldn’t, didn’t you?” His words are slow, even. Unjudging.

There’s no running away from it. Denki feels the burn of tears again but stubbornly refuses to let them fall. He pushes himself to sit, resting his forehead against his knees and breathing in deep. Back after the ordeal in the Heart, he’d explained his trauma to all of them—his fear and panic and what had gone wrong. But this? 

He’s seen how the others’ expressions tighten at the mention of ley-hunters, magic-thieves, rasyakiin. And now, with it clear to all of them that he doesn’t even have the leftover embers of a simple human affinity – they must be connecting the dots, asking questions.

After all that Aizawa and Yamada have offered him, he owes them this.

“My—my accident… was at a ley-line.” He tightens his grip on his calves. “I shouldn’t have tried to take its power, I know that now—” he flinches at Aizawa’s sigh, but presses on, “—and ever since that day, I’ve never been able to do any magic, none at all. Whatever it was that kept me alive, it took my affinity as payment. It’s… it was more than fair. I’m sorry. I deserved this—I’m sorry .”

The ex-siren at his side says nothing, and Denki doesn’t dare look up. Seconds pass that feel like minutes, stretching on and on—until at last, he hears what sounds like the chair creaking, a huff of effort, and a hum.

“Is this from the guppy?”

The unexpected question catches Denki off guard; he finally glances over to see Aizawa turning the string message gift delicately between his water-darkened fingers. 

“Y-yeah,” he says, swallowing.

Aizawa hums again. “He’s been asking after you for a few hours now. Do you want to see him?”

A few hours. The guilt weighing like lead in Denki’s chest doubles, still not comprehending this casual line of questioning after the truth he’d just unloaded onto the man beside him. He wants to say yes, of course, needing Hitoshi like he needs air, but…

“He’s probably upset with me,” he admits, his own words stabbing deep and twisting. “ Y-you should be upset with me—I…” he tries to find the right words, but can’t, shrugging.

Aizawa’s reply comes slowly. “If I thought you to still be the stupid, selfish, reckless human you were back then, perhaps I would be more upset than I am.” He pauses, and raises the string message. “Do you know what this says?”

Rendered speechless, Denki shakes his head.

A grunt. “I thought not. Well.” Aizawa picks up the dangling, beaded cords hanging from the loop one by one. “It’s a pair of statements. When the strings switch color, it’s a new sentence. Not complicated.” He shifts them apart, and gives a long sigh before continuing. “The first part’s a saying among our people. ‘Chaos carves the current’s course.’ It’s… in recognition of fate, that the broader strokes of the future are decided for all those who are touched by its magic.” 

Denki watches the tightening of the man’s expression, a moment of frustration and pain, then it subsides. Quietly, he asks, “And the rest of it?” 

Aizawa glances over at him—the first time they’ve made eye contact since Denki’s admission—and the look contains none of the accusation Denki’d been mentally preparing for. No anger, no disappointment; only, somehow, pardon.  

Then the ex-mer hangs the string message on the post of Denki’s bunk. “Says, ‘I’m glad it was you the waves carried me to.’ We all recognize how lucky he was that day. If it had been anyone else…” he lets it trail off; there’s no need to finish.

Denki understands. 

“I’d like to go see him now,” he struggles to say with the tightness in his throat.

Aizawa nods and gets to his feet, fetching the nearby wheelchair even before Denki asks for it.

It’s something he can appreciate more than ever, as shaken and drained as he feels. When settled, he even lets Aizawa push him, relaxing into the arrangement despite it being an extension of trust he’s offered to so few over the years. Slowly, gradually, he settles to one side of the chair. It’s an odd realization; he doesn’t need to fight for every sliver of independence here, not with these people. They really do feel like… family.

As if on the same wavelength, he hears Aizawa take and release a deep breath. Then, “Kid... Hizashi and I meant what we said.” He pauses. “Bond or no, we’re not going anywhere.”

Denki doesn’t trust himself to speak with the growing wetness in his eyes. So he nods, but at the soft brush of thumb pad over his C7, lets out a shaky exhale.

They wheel out to the stern and wait. Yamada is there holding Eri, immediately moving to pull Denki into a tight, apologetic hug. “We told Hitoshi to go clear his head, but he’s on his way back now.”

And when Hitoshi does breach a few minutes later, reaching out, Denki doesn’t hesitate to stumble from the chair to meet him. He hears the calls for caution from behind but pays them no mind; sinking down to the deck where there are strong, damp arms to meet him.

He hiccups apologies into the curve of his siren’s neck, listening to the quiet crooning that reverberates through Hitoshi’s chest. Reassurance put into song, counterpart to the tight embrace around him, the seeping tangled feelings passing between them at the contact. Then the cold form beneath him tilts and shifts, and they crash into the even colder ocean. 

It’s enough to shake Denki from his mumbling, so he catches his breath, holding on tighter as the waves lap at his chest. He reaches for the siren’s thoracic fin and strokes it shakily. The crooning subsides in a heartbeat as Hitoshi’s attention is gathered. Denki pulls back enough to look him in the face.

“I… I get it if you’re upset w-with me,” he starts, pushing through even as Hitoshi immediately starts shaking his head. “I’m sorry—I really hoped —”

He’s cut off by a kiss.

Fast learner, Denki thinks weakly, relieved that Hitoshi is dedicatedly keeping them afloat, as his own arms go to jelly around the other’s neck. 

But Hitoshi pulls back shortly after, chirruping as he noses at Denki’s jawline, cheek, temple, then shifting so their foreheads meet. The shared sensation isn’t a rush this time, but it feels more intimate than ever as Hitoshi cradles his face—

—and murmurs into the space between their lips, “Denki… if you’ll have me.”

Oh.

The tears spill over, the last of his worry falling to pieces like a thousand shards of sea-glass. He nods so fast he goes dizzy, crumbling into a wreck of sobs and shivers and relief held together only by willpower and his would-be mate. 

They can’t stay in the water forever, though. When he is hauled back out to a mixed bag of lecturing and relieved looks, Yamada bundles him up in a load of blankets (appearing rather misty-eyed himself). Neither of the men try to make him leave the deck, to his relief—Hitoshi slides into the repurposed tub and Denki’s more than content to drag a lounge chair alongside it, finally feeling at peace for the day.

Then Nemuri steps out of the cabin, uncannily silent.

Yamada is the first to notice her, and his posture changes in an instant. “Nem, what is it? What’s wrong?”

The sea witch starts to smile, then lets it fall. “Well,” she begins shakily, “As… some of you are aware, I’d put out… feelers, here and there, to have early warning on any rasyakiin movement.”

Aizawa slowly gets to his feet, staring at her.

She runs a hand back through her hair, and closes her eyes with a grimace. “I expected them to take longer than this. Eri’s surge must have been stronger than we thought, more noticeable, for them to catch on already—”

“Nemuri,” Yamada interrupts, “what are you saying?”

“They’re coming for the ley-line’s magic again,” Aizawa murmurs. His voice is monotone, devoid of any of the dozen emotions currently wreaking havoc in Denki’s chest. But the man’s too still, too intense to be calm; Hitoshi’s low hiss and fear-flattened aural fins say everything his new father figure does not.

Nemuri nods once, sharply. “They’ve already begun mobilizing in ports around the Pacific. My best estimate right now is at least a dozen boats, but… that’s no doubt only the beginning.” 

Silence meets her words.

“There’s no more hiding, boys,” she continues, voice wavering. “The hunters have the scent once more. We need everyone we can possibly get on our side, and we need them soon. ”

Chapter Text

The evening’s flurry of activity bleeds well into the twilight hours of the morning as they lay out their options. 

Nemuri says she has some favours she can reel in from contacts at various ports, but it’s not going to be enough. Too big of an ask to sabotage readied ships, and barely enough time to track which vessels are owned by the rasyakiin, at that.

Yamada palms his phone and disappears for a few minutes. When he returns, he’s wearing a grimace.

“The Shinkai Maru felt the surge too,” he explains, sliding off his sunglasses and rubbing at the bridge of his nose. It’s the first time Denki’s seen him quite so sapped of the energy he’s usually overflowing with. “Might be time to break our silence and ask for help. Nezu will hear us out, yeah? He’ll have some harsh words for our secrecy, but the whole expedition listens to what he has to say.” He smooths his thumb and forefinger over his mustache, contemplating with a faraway gaze. “Don’t see any way around it, if I’m gonna be honest. The Applied Magic division’s help might be our best chance.”

Aizawa scoffs. “Or they’ll make things worse.”

“There’s the cynical Shou I remember,” Nemuri says with a laugh, though it’s a strained one. 

“Better cynical than unprepared.”

She hums. “At least we have Eri with us. They don’t need to know about her involvement.”

“And the relics from inside the barrier,” Bakugou points out, arms crossed. He and Uraraka are sitting to the side, mostly relegated to listening, just like Denki himself. “What the hell’d we lug those up for if not to keep the boat safe? Aren’t the spells on them exactly for protection?” 

The line of Aizawa’s shoulders relaxes a titch. “…They are,” he admits. “Eri will be fine. But the ley-line itself is the issue. We don’t have enough bodies to defend it.”

Hitoshi murmurs something quietly, hesitantly, drawing all of their attention.

After a moment, Aizawa translates the context by way of response. “They won’t be thrilled to see you again.” 

Denki frowns, gears turning as he tries to understand—then it hits him. “Wait—you can’t possibly mean the trench mer,” he exclaims, alarmed. “Hitoshi, they tried to kill you. You’re not going back there.”

Hitoshi bristles slightly as he replies.

“Whether or not they would believe you now,” Yamada says softly, “We’re not willing to risk your safety.”

Beside him, Aizawa nods, scanning across the expanse of the map table. “There’s no doubt that they know the ley-line woke up. If they choose to act on that, they’ll come to us.”

And with that, they wind down well into the twilight hours, finally agreeing to break apart the meeting and get some rest. They’ll have the day to get ready, by Nemuri’s estimate, and if tomorrow’s going to be a sleepless night of watching and waiting, it’s best to take what few hours they can manage for now.

However, only scant hours later, Denki is gently stirred awake by the purring engine of an approaching sea-doo, the hum buzzing through the walls. He’s about to close his eyes again, savoring the last dregs of sleep, when suddenly there’s a sharp yell—unmistakably Bakugou’s—and a splash. He throws off the covers, fearing the worst.

And as he reaches the deck, the yelling has reached a new peak, accompanied by another splash and high-pitched hissing that sets Denki’s hair on end. Nemuri’s in the water, teeth bared; Bakugou’s scrambling to get on the boat behind her.

“More fucking fish,” his pale-haired friend spits, wild-eyed and slightly shaky as Yamada reaches them with a towel in hand.

Yamada laughs under his breath, staring. “Looks like you were right, Shou.”

Denki leans over the railing, ignoring the sharp bark of ‘Careful’ from Aizawa and the fist wrapped in the back of his t-shirt. He freezes in shock and delight almost instantly.

There are two of them floating there, vibrant and alive and real, and Denki can’t help the grin that steals over his face. One is larger even than Hitoshi, bulky and muscular, his scales mottled shades of crimson; the other smaller, clearly female, and thoroughly pink. Gorgeous. They’re both gorgeous —he’s smitten with their very existence. And, if he correctly recalls the notes he’d taken based on the mer biology book Yamada let him borrow last week, both of them are coral mer—not the dangerous kind.

Comparatively, anyways.

Neither has noticed him yet; they’re hunched defensively by the drifting sea-doo, their aurals pinned back as they return Nemuri’s warning stare. The pink female chirps something that has Nemuri growling in response, and big red raises his arms to the surface, the scales on them so broad and thick they look like plating. 

“Where’s Hitoshi?” he asks breathlessly. 

Aizawa’s not far from his shoulder, staring just as openly. “On his way.”

Adult though she is, Nemuri appears slight and almost fragile in her humanoid form compared to the two full-bodied mer. Denki’s spent enough time around Hitoshi that he can read the pair with ease. They’re not exactly pressing the aggression, reminding him of spitting kittens, equal parts confused and unnerved by this two-legged being posturing like one of their own. 

The minutes drag on, until at last a purple shadow slides along the outside of the boat, and Hitoshi breaks the water with a stare.

If Hitoshi couldn’t see them floating there with his own two eyes, coiling and on guard as he quietly approaches the boat , he never would have believed it.

Logically, he knows it’s been less than a moon since he’d been forced from the colony—barely a ripple on the tide compared to the many seasons he’d been one among them instead. But for some reason the sight of Mina and Eijirou at the surface drags up something like an ache from the depth of his chest. They look so different in the glow of the sun. It suits them.

He breaks the water with a gentle noise, but it’s enough. Everyone glances his way—

And in an instant, Mina screeches, launching herself at him bodily and dragging him back under the waves. He thinks he can hear Denki call for him, but it’s nearly drowned out by the constant stream of shocked babble from his colony-kin.

Mina has lodged herself to his chest like a barnacle, so it’s Eijirou’s baffled, relieved expression Hitoshi sees most clearly. The big red half-breed chokes out, ≈You’re alive?≈ —then he too joins in the somewhat uncomfortable embrace, squeezing them as a group until Hitoshi nearly fears for the stability of his ribcage.

≈Get off,≈ he squawks as they bob back to the surface as a group, though it’s at odds with the warmth spreading through his core at their reunion. He reaches for a rung on the side of the boat to stabilize himself, chirring at them with half-assed reproach even as the corners of his mouth twitch upwards.

“Friends of yours?” Denki asks in the walker tongue with a nervous laugh, and Hitoshi can’t help but grin up at him. 

But the question also draws the attention of his companions, who fall quiet as they look back and forth between him and Denki. Mina’s eyes glitter with interest; were they not in the presence of walkers, he has no doubt she’d be burying him in questions about the sun-haired boy, but instead she simply stares up at him with fin-shivering intensity. Worse, he can see how this newfound attention seems to unsettle his markless mate.

So Hitoshi shakes the pair off and pulls himself up the side of the boat until his muscles strain at the surface-weight, chirring softly. He switches to his lungs, relaxing the sides of his neck until the gills lay flat, and takes a deep breath. “Yes. Safe,” he replies, without letting his gaze waver.

That seems to relax everyone on the boat, for now.

Denki moves to sit down, and while Hitoshi wishes he were up on the deck to reassure him, he lets himself relax back into the water. Besides, sosvii Aizawa and Yamada are there to bracket his mate on either side. He won’t be left out of the conversation with their help.

Which makes him pause. He looks at sosvii Aizawa ( Shouta, the bond tells him, but he’s too stubborn to change his ways.) Hesitantly, as he’s never been able to ask such a thing before, he murmurs, ≈…Can I introduce you?≈

Ignoring Yamada’s weird walker coo (and Denki’s clueless expression), Aizawa huffs. ≈You may.≈

Giddiness zips down Hitoshi’s tail and he turns back to his colony-kin, flaring all of his fins with pride. Eiji and Mina are already gawping like hatchlings at the implication, so Hitoshi can’t rein in his smug excitement as he tilts his head and announces, ≈Those are sosvii Aizawa and Yamada, my pod.≈

He hears Aizawa grunt—okay, fine, it’s his pod, technically. Hitoshi acknowledges it with a chirp and a flick that brings a laugh from Yamada, who then translates the interaction to— oh yeah.

≈And…≈ he turns to look at the bright-smiled, stunning boy between the two adults, who’s already beaming back at him. ≈This is my mate,≈ he adds, before switching to walker-tongue. “Denki.”

The sound of his name only serves to widen that smile, and Hitoshi’s body fills with seafoam and bubbles and lightning, barely containing the trill that works its way up from the depth of his core.

Nemuri introduces herself, and with a bit of prompting, Denki’s vent-tempered walker friend does the same. Everything falls more gently into place that way, with Eijirou and Mina each speaking for themselves, their initial wariness-raised fins flattening against their scales once the adults nod at the introductions with little fanfare.

Mina, however, has never been one for subtlety, much like the dwindling other pure-blood corals back in the deep. She glides closer to the boat with an eager display of her elaborate tail-pattern, showing off like a dumb, fancy reef-fish as she floats into Nemuri’s space. 

≈You’re not a walker,≈ she chirps, gaze clearly lingering on the muddy blue scale-pattern gradually surfacing on the older’s visible skin. 

Hitoshi wants to pull her back, chitter at her for such a blatant display of disrespect towards an adult who could string her up by her tail, but he stops himself. Despite how she acts, Mina’s not really a kelp-brained hatchling anymore, and the fact that she has survived as one of the few pure coral-fins in the trench is a testament to her stubbornness. The challenge in her tone is testing the waters.

Nemuri smiles in reply. It’s a sharp, knowing, dangerous thing that has even Hitoshi’s fins pinning nervously. ≈And you’re not extinct.≈ He sees Mina and Eijirou echoing his instinctive alarm, both of them sinking lower in the water. It seems to be enough to satisfy Nemuri; she slowly blinks. ≈We both have our ways of surviving. Now, what are you here for, little guppies?≈

Eijirou is the one to reply, sharing a look with his podmate before hesitantly asking, ≈Is it true that there’s a new royal? We felt something, but the elders wouldn’t tell us what it meant. We overheard some talk, and we weren’t allowed to leave, but—≈

≈But we had to know ,≈ Mina adds, her tail flicking the surface irritably. ≈It’s okay if they’re mad, but we couldn’t just drift about like nothing had changed, not when…≈ she cuts herself off with a whine, resting a hand over the base of her throat. ≈When it’s so obvious! It feels like my mind is clearer than ever!≈

Hitoshi is flaring in agreement before he realizes it, heart fluttering as he remembers the sensation. Like his first breath of surface air, and Denki’s bright smile, and Aizawa claiming him for the pod, and unmistakable hope more powerful than any current, all rolled into one. He glances at the others and notes his pod-sire’s half-lidded gaze, the soft smiles on everyone’s faces. They all remember.

“That sounds like the trench-dwellers, alright,” Aizawa grumbles in the walker-tongue as Yamada rises and disappears further into the boat. Then the land-bound siren translates the same back to Mermish, which has Eijirou and Mina blinking up at him in surprise, much as they’d done with Nemuri.

Mina swallows. ≈They were talking about how the best place for a royal is the trench. Most walkers don’t dive that deep, and any that do could be dealt with easy, ‘cause they’re weak and blind. The royal would be protected—≈

Hitoshi hisses sharply, interrupting, anger rising in him like a tidal wave. He feels similar concern radiating from Aizawa. 

Perhaps in response to the reaction, Denki drops to sit at the boat’s edge, confusion knitting his brows and pulling downwards at his lips. “What? What is it?”

“The council of the trench will likely demand that Eri be taken down to them,” Nemuri explains, and then Denki too is shaking his head slowly.

“ No, ” Hitoshi states verbally this time. It’s odd not being the one misunderstanding walker-speech now, though, so he huffs in annoyance and backs up into Denki’s shins when the blonde reaches for him. The contact settles him a bit, and he forces his fins to stop flaring so defensively. ≈She'll be in our pod. We can keep her safe.≈

He tilts his head back, his horns knocking against Denki’s legs, and catches his other half’s golden gaze. Our pod, he thinks again, blinking slowly up at him. Although his silly, loyal walker couldn’t have translated, Denki’s pale face flushes gently with pink. He’d understood enough.

≈They won’t believe that,≈ Mina murmurs. 

And then, as if called by a hidden current, Hitoshi’s magical core alights into gentle warmth—a now-familiar sensation. Though he hears footsteps upon the deck, he doesn’t need to turn. He can feel the breathtaking pulse of energy through every nerve, can feel her nestled up against Yamada’s much subtler magic. Safe and sound, widely-felt, but theirs to protect. 

It’s as if something immeasurable has shifted; both Eijirou and Mina go impossibly still and silent. Their wide, unblinking eyes are locked on the little sleeping royal in Yamada’s arms. 

Hitoshi knows the sensation of not being able to look away. Eri’s hold is strong. ≈Make them believe,≈ he murmurs. ≈Whatever it takes.≈

Mina chirrs, stilted and broken, and only manages to tear her attention away to stare back at him hopelessly. ≈You know we have no say down there. Without them seeing her themselves…≈ she lets it trail off as her aurals pin back with worry.

It’s Aizawa who breaks the stillness that follows, getting to his feet. ≈A moment,≈ he says stiffly, keeping his eyes low as he trudges towards the cabins. Hitoshi reaches for him mentally, testing the new bond, but what’s on the other end feels insurmountably vast and quiet. If Aizawa’s feeling anything, he’s keeping it well-hidden. He returns only a minute later with some string that he’s already looping and knotting into a message. A request for help.

Weaved in with the normal strands are several black ones – Aizawa’s hair, without a doubt. It piques Hitoshi’s curiosity, as it implies they might know him – but then he notices the lone, long silvery-blue strand of Eri’s. He bristles slightly; when had they taken that? Had they asked? She wasn’t awake yet!

But Yamada gives a soft gasp and steps toward his mate. “Shou…” he murmurs, hesitantly ghosting a hand over the other’s shoulder.

Hitoshi looks again at the strand. No, it’s slightly too blue for Eri’s hair, he realizes. An easy mistake to make. Now he’s even more curious, but the world-weary look on his sosvii ’s face stops him from asking. Instead, he waits for Aizawa to finish the message, watches the man run his thumb over the final result with a hard-to-measure look, then holds up a palm in request.

Aizawa meets his gaze and sighs almost imperceptibly, and carefully sets the rolled-up bundle in Hitoshi’s hand.

And just like that, Hitoshi understands why he’d taken it for Eri’s. He doesn’t need to read the knots; the power in that single pale blue strand is unmistakable. At a loss for words, he carefully passes it along to both Mina and Eijirou, only to see his own shock reflected clearly on their faces.  

Above him, Denki asks, “What’s it say?”

There’s a moment of silence. Then, “I’m calling in a debt,” Aizawa responds. 

Hitoshi stares at the ex-siren, his pod-sire, feeling like he’s seeing him again for the first time.

Aizawa turns away from their eyes with slumped shoulders and a lowered gaze, trudging to the door of the boat’s belly. With an exhausted weight in his tone as if he’d been Singing for moons, he adds in a rusted-over voice, “One they can’t ignore,” and disappears inside.

Denki doesn’t really understand what’s just happened, but he reads the mixes of awe and melancholy on the others’ faces and knows there’s something more to the message than the simple explanation Aizawa had given. The pink mer is staring at the strings as if they’re just as compelling as Eri, and Hitoshi’s gaze hasn’t lifted from the door to the below-deck, but nobody is saying anything and it’s making him a tad anxious, if he’s going to be honest.

That is, until Nemuri inhales deeply and breaks the spell, turning to them. She settles a hand on Yamada’s shoulder. “It’s time to broadcast, don’t you think?”

Yamada sighs and runs a hand through his hair. “Seeing Shou, I can’t imagine it’ll amount to much. The others might be in the same predicament.”

“You started the project for this reason, ‘Zashi.” 

He nods. “ Yeah, but—” 

“In order for them to make the choice, you need to give it to them,” Nemuri says, reaching for Eri and pulling the royal child into her own cradling arms with a coo. “If they’re listening, then they’ve probably been waiting all along, right?”

Denki clues in. “You’re going to use the radio to broadcast for help?” he asks, pushing himself to his feet and grabbing his cane. It’s such a cool idea. He imagines what it would have been like to get that kind of call to action from one of his favourite radio stations as a kid. And yet… his face pinches. “But lots of people listen to that – couldn’t it maybe draw the wrong kind of attention?” 

A genuine smile pulls across Yamada’s face and he ruffles Denki’s hair. “How about you give me a hand and I’ll let you in on the secret, listener?”

He sees off Hitoshi first; the purple mer seems eager to have the chance to catch up with his old friends, indicating he’s going to accompany them for part of their journey back to the trench. Then Denki follows Yamada to the comms station, set up with basic recording and radio broadcast equipment. 

There haven’t been any new recordings of Mic at Seaside Radio for years now, Denki knows, and so it’s with an eager quickness to his voice that he asks, “Are you making something new today?” 

Yamada shakes his head with a grin. “Nahh, this one I’ve been holding on to for a while. Long before your time, youngster. But… you might still find that you like it.” 

He rolls over to the monitor and clicks through several directories until he reaches a folder with a single file. The label on it reads ‘ Last Call’. Then, with a widening smile, he hands Denki a headset and hits play. 

It sounds nothing like the station’s regular music, to Denki’s immediate surprise. He’d always tuned in to Mic at Seaside for the high-energy mixes, the closest thing they’d been able to get to a beach party DJ back home in his teenage years. Yamada laughs at his clear befuddlement, but Denki’s not against the track at all. It’s just… different. No vocals at all, only steady instrumental like a heartbeat—until he hears a throaty trill, a drawn-out hush, and just like that, recognition hits.

“You—you sampled Mermish!” he exclaims, tapping one earpiece. He remembers the soothing music from the day before, and understands now why that was familiar. “That’s how you’re going to control who hears the call for help! Does that mean there are many other sirens on the surface? Like Mr Aizawa and Nemuri?” 

Yamada nods along to the beat, giving Denki a brief wink. “Got it in one, kiddo.”

Denki keeps listening. The Mermish is a lot more lyrical than he’s used to hearing from anyone on board. After another half minute of trying to pick out any sounds he’s familiar with, he comes to another realization. He pulls off the headset, holding it around his neck. “That’s not Aizawa speaking, is it?” he asks more quietly. 

Yamada smiles again but it doesn’t reach his eyes. “Heh, no, Shou’s fiercely mic-shy. This is an old friend of ours.” A brief pause. “A friend of everyone. Just that kind of guy, y’know?” 

He turns away and gets to work on the radio equipment, expertly setting up the system with age-old familiarity, his mouth in a tight line. At last he presses a button, and sits back with a sigh, chewing on his lower lip. “That’s that. It’ll replace the noon and midnight reruns.”

“Professor,” Denki starts hesitantly. “That… old friend. Is he the same one that Aizawa said he feels in Eri? Earlier, was that his hair?”

Yamada looks taken aback for a moment, but then grins broad and warm, if a little sad. “Little Sherlock, aren’t you? Yeah, listener, that’s him.” He crosses his arms behind his head, thoughtful. “…Oboro. His name was Oboro.” He says it uncharacteristically quietly, as if afraid to be overheard, staring off over the water. “Big guy was the royal before Eri, not he’d ever say it outright. Back when all I owned were my ukulele and some grand ambitions, he overheard me playing and invited me to perform for the colony. Much to the displeasure of his grumpy, overprotective siren podmate.” He side-eyes Denki with a smile.

“Mr. Aizawa?”

“Bingo. Thicker than thieves, those two were! One the laid-back prince of the coral-fins, the other his self-appointed bodyguard.” He nods to himself, or perhaps to the ocean, agreeing with the phantoms inside his head. “Shou was an outsider to the colony too, in a way—a deep trench mer by birth, and the only one who didn’t praise the tides Oboro swam on. But that’s a siren for you; they make an effort to never seem impressed by anything, if you ask me!” 

Denki laughs at that, leaning back against a post. “I can see it,” he agrees, thinking of Hitoshi’s early mannerisms.

“Mmm.” The man smiles again, expression soft. “But once you earn their loyalty, they’ll impress you at every turn.”

Denki looks out over the water; he couldn’t agree more.

The breeze picks up, wrapping around him like a loved one, carrying bits of noise from elsewhere. He takes a deep breath and lets the cool air rest within. He tastes the salt of the sea on his tongue. And, if he focuses just right, he swears he can feel Eri’s subtle heartbeat through that strange, novel sense at the back of his mind, step for step with the gentle waves rocking the boat. 

But while the quiet companionship is nice, it doesn’t last. After a few minutes of comfortable peace, Yamada gets to his feet with a long sigh, and excuses himself to go speak with the director of the Shinkai Maru about backup for the incoming fight.

Somewhere below, he can hear Bakugou and Nemuri discussing how to best defend the Midnight Lady. Bakugou mentions a cannon, and when Nemuri doesn’t dismiss the idea, Denki feels the stirring of anxiety once again. A cannon? Just what would they be coming up against?

Maybe it’s because the threat doesn’t feel genuine yet, just another piece of the surreal experience that has defined the last few weeks of his life. Still, it doesn’t take much to remember the ruins on the undersea plateau and be reminded of what his fellow humans have been capable of. Would the laws make any difference? Would they be able to stop the poachers without violence this time around…?

Denki waits on the balcony for an hour or so longer, listening to the distant voices and taking the time to let his squishy mental processors rest. Some might call it selfish when there’s so much he could be doing to prepare, but he’s got an arsenal of words and some mental health websites he can pull up on his phone in a heartbeat for those who would give him any shit. It is its own kind of preparation, in a way. 

He relaxes, and breathes, and listens. It only comes to a halt a little while later when he hears the telltale splash-thud of someone pulling themselves from the water. Hitoshi must be back.

He takes the opportunity to ignore the growing seed of doubt, and makes his way down to the deck.

He gets there in time to see Hitoshi slide somewhat gracelessly into the repurposed Jacuzzi and receive baby Eri from the arms of a mollified Uraraka. The latter is speaking in eager, hushed tones about the child, everything from even asleep, her magic is stronger than any I’ve ever felt to isn’t it just incredible how she switches between her lungs and gills completely unconsciously? 

Hitoshi, for his part, chirps in agreement and flares his fins with pride, curling the living, breathing hope of his people against his chest. It strikes a deep, fond chord within Denki, who lingers by the railing for a few seconds longer until Hitoshi seems to sense his presence and turns his way. 

The mer makes another pleased sound, then with his oddly-accented and broken Japanese, calls out, “Denki. Why look? Come.”

Uraraka laughs at Denki’s caught expression; sue him, hearing Hitoshi’s developing grasp of the language continues to give him butterflies. She climbs out of the pool and picks up her towel. “Well. From my limited experience regarding you, she seems to be perfectly healthy, so don’t worry too much, Hitoshi.”

Denki frowns. “Worry?” He glances back to see Hitoshi close his eyes and flick his aurals, as if to say, Not worried. 

“Because she’s still asleep. But I don’t blame her—that’s a lot of power she’s keeping a lid on! Some human families would give anything for a baby that’s so quiet, you know.” 

Families. For the second time in as many minutes, Denki can feel heat rush to his face.

Uraraka’s clearly playing with him, too. “I’ll give you two some time alone,” she says with a wink, poking one of his reddened cheeks as she dries off. “Be mushy and adorable in peace!”

Thankfully, Hitoshi seems immune to the typical human mortification about PDA, so the minute that follows the biologist’s departure is only particularly awkward for one of them. Hitoshi gives Denki’s blush a bemused look, repeats Come and a quiet chirr, and gently slaps the surface of the tub’s water with the end of his tail. 

Denki hobbles over, and manages to maneuver himself to the ground without much issue, sinking his calves in the cool water as he sits on the side. His braces creak as he does so; he’ll need to oil and perhaps even reseal them soon. He’s about to say as much to Hitoshi when he realizes the siren’s still watching him anyways, with that familiar superhuman half-lidded intensity he’s never completely gotten used to. Predatory, or maybe possessive. It’s long stopped being something Denki is wary of, but it raises the hair on his arms just the same.

“What’s up?” he asks, half laughing for lack of a better not-prey response.

Of all things, he’s not expecting to have Eri held out to him.

Denki instinctively leans away, hands raised in protest. “What? No—n-no that’s—I can’t,” he stutters out, meeting Hitoshi’s calm gaze over the child’s pale head. “She’s too important, what if I—what if I drop her?”

Hitoshi pauses, and for a second Denki thinks he’s in the clear. But then the purple mer says something in his own tongue and pushes closer. He drifts up further into Denki’s space, forcing Denki to spread his knees, and parks himself there resolutely. Then he stares directly back into Denki’s own wide eyes and repeats his mystery words. 

Eri’s between them now, close enough for Denki to touch without reaching—so he does, hesitantly, running a feather-gentle hand over her long curls of ethereally-floating hair. They match the pearly scales of that cover her tail and climb the line of her spine and fins, disappearing beneath the draping decorative wrap Nemuri had fitted her with.

And then before he knows it, she’s being eased onto his lap, and he holds his breath.

Denki’s never held a human child, much less another species’ or one nearly as important as the little royal whose head sleepily rolls against his sternum. He feels the twitch of her tiny, delicate aurals as she settles and it startles him; it’s easy to see her as a sort of divine statuette with her proclivity for sleep, but no, she’s really, truly alive. And heavier than he expected, if he’s being honest. It brings a nervous laugh bubbling up out of his chest.

“Okay,” he says. “This—this isn’t terrible. Just don’t go anywhere.”

He can feel the moment her lungs hiccup into action, marveling at how instinctive and easy it seems for her compared to the panic-inducing struggle he remembers from Hitoshi. Where her back is curled against his bare arm, his skin tingles oddly but not unpleasantly. Uraraka was right; she’s incredible.

Only when Hitoshi eases his long body from the pool does Denki pull his gaze away from studying Eri’s long, pale lashes and the slight movements behind her eyelids. The purple mer curls around him, everything from his relaxed fins to the purr-like noise that rumbles through Hitoshi’s chest as he set his chin on Denki’s shoulder signaling nothing short of contentment. 

Yeah. This is fine, better than fine. His presence is enough for Denki to relax his tense posture, and shift Eri more comfortably in his hold. Everything is alright.

Well, almost everything.

“I don’t know what to expect tomorrow,” he admits quietly, tilting his head sideways against Hitoshi’s. The words didn’t sound nearly as vulnerable when they were inside his head, but out in the air, they’re like an open wound.

The arm that Hitoshi isn’t using to support his upper body slips around Denki’s waist, pulling him more snugly back against Hitoshi’s cool body. 

“Don’t worry,” the siren replies, parroting Uraraka’s earlier words. “Safe.”

“It’s hard not to worry, my guy. I’m not built for conflict, and I’m not even really that good at diplomacy unless there’s a need for a professional rambler, y’know? What am I gonna do, talk their ears off about deep-sea diving machines and ship maintenance protocols?” He takes a deep breath and runs a hand back through his hair. “I can probably keep this boat afloat, or throw together some defensive measures on the fly, depending on what they’re coming at us with. But if it turns into a real fight, I dunno, maybe—”

Hitoshi cuts him off with a hum, moving to mouth at the back of Denki’s neck and giving him a quick, gentle nip that feels a lot like chastisement. “Safe,” he insists again. 

Denki shivers involuntarily. “As in what, you’ll keep me safe?”

“Mm.”

“You can’t be distracted looking after me, ‘Toshi. You’re like… our trap card, or queen piece, or surprise attack, or something. You’ll have enough to deal wi— ow, stop that, you oversized piranha.” 

The mer chirps indignantly, but ceases his nipping, instead opting to pull himself more fully around Denki so they’re face to face once again. His eyes are slightly narrowed, but whether it’s from insult or consideration, Denki can’t tell.

“You know I’m right, though,” he offers with a dreary half-smile, watching as Hitoshi’s aurals flick and fold as the siren struggles with an expression extraordinarily similar to a pout. By the growing furrow between his brows, he can tell Hitoshi doesn’t have the words he needs in Japanese available to him. So he cups a hand around the back of the siren’s neck and pulls him in, closing the distance between their foreheads.

The tension drains from Hitoshi in a heartbeat, a few speckles illuminating gently among his scales. Try as the siren might to hide his own worry about the upcoming confrontation, the echoes of it reverberate between them. 

Hitoshi sighs and clicks a few times, then closes his eyes. “Sorry.”

It gives Denki pause. “For what? Don’t apologize for having an important role to play. Or for being worried—we all are, I think. And you shouldn’t need to protect me anyways, right? I’ve got nothing they’ll want.”

But Hitoshi isn’t quite having it. “Apolo-gissse for… ah…” he murmurs something in Mermish, frown growing as he struggles with limited vocabulary to copy. “…not safe. To… need fight.”

Denki takes a few seconds to try to reason out the meaning, but when he does, his heart aches. “Danger? You can’t possibly be apologizing for this whole situation. You’re only doing what needs to be done to protect Eri. To protect your home. That’s important, Hitoshi.” 

“Important to protect mate,” the siren mumbles into his cheek.  

The words set the butterflies in Denki’s lungs fluttering, and he knows his own face must be as red as Hitoshi’s is bright. He’s never understood Hitoshi to be shy , not in the slightest, remembering the mer’s smug proclamations even deep in the heart of the ley-line. But maybe this is what his siren’s—his mate’s —moment of insecurity looks like, a subtle admission in the calm before the storm, a fear of not being quite enough.  

He pulls back a fraction, tapping Hitoshi’s cheek with the pad of his thumb until those pools of vibrant purple and endless black lift to meet his gaze. 

“I’m not going anywhere,” he says. “I’ll stay out of the way of danger however I can. So you pay attention to what’s happening in front of you and not about me on the back lines, yeah?” It’s hard to say out loud, when every fibre of his being wants to ensure they’re never separated for even a moment – but it’s what makes the most sense. 

Hitoshi flares his aurals and touches their heads again, releasing a gentle, wordless croon as soft as a breath. It’s a new one, like distant whale song, and brief—then he tilts his face and kisses Denki.

The warmth of it chases through every inch of Denki’s body.

Between them, Eri stirs.

They both immediately break away and stare down at her. The tiny ivory girl wiggles slightly, shifting her weight towards Hitoshi and slowly spreading her aurals as if pleased. For all Denki’s bated-breath anticipation, she doesn’t wake up, but it’s still the most movement she’s made on her own as far as he’s seen—and perhaps as far as Hitoshi’s seen too, if the siren’s statue-still alertness is to be believed.

Soon, Denki thinks. Maybe not soon enough to avoid the conflict only hours away, but this is proof enough for him that Eri isn’t going to sleep forever. He has a hunch, inexplicably or perhaps just desperately, that seeing her will be enough to change anyone’s mind. How can it not?  

Yeah. Everything will be fine . Chaos carves the current’s course, and all that.

As he carefully releases the child back into Hitoshi’s waiting arms, watching the way his mate cradles her like she’s his very own, he wills himself to believe that there’ll be a happy ending. That if they make it through the night, they can make it through anything.

The thought of the alternative is too much to bear.

Chapter Text

“You can’t hide it from me, you know.”

Shouta hums, easing open his eyes a fraction. He has to solve the puzzle of meaning on context alone, initially, until he touches his mate’s mind and understands. He turns his face against the warm, soft skin of Hizashi’s chest. Part of him wishes the blonde would keep carding those elegant musician’s fingers through his hair and not bring it up at all. 

The other part of him knows it’s a conversation they need to have. Just in case.

“It’s like you’ve been trying to keep a lid on it all day. I just can’t figure out if it’s for your sake or mine, Shou.”

Shouta sighs resignedly and flips onto his back, pulling one of the bedsheets up. “…Mostly mine,” he admits. 

In his peripherals, Hizashi nods, chewing on the inside of his cheek. 

The quiet pensiveness is a poor reflection of the blonde’s naturally sunny behaviour, but it’s the mood of the night for both of them, apparently. Then again, it’s hard to be anything else when faced with the realization that this could potentially be the last night.

Hizashi winces.

“Sorry,” Shouta murmurs with a twinge of guilt, raising a hand and pressing the palm into his temple. “I suppose it’s for both our sakes after all. I just…”

When he doesn’t continue the statement, Hizashi nods again. They don’t need words, not really, thanks to the bond. But the air feels cold and empty without them.

Hizashi rolls onto one side, facing him, and tugs the duvet to his shoulder. Those long fingers of his encircle Shouta’s wrist and ease the hand away from his face, pulling the appendage down between them. Their fingers intertwine as naturally as breathing.

“I’m scared too,” his mate says.

Shouta knows. He can feel it, has been feeling it for the last day. A muddied mix of both of their worries, fears, and regrets resting like a mire between them, growing less traversable with each passing hour. But if they don’t try tonight, then when?

“If we can hold out until the others get here, we’ll lay the problem to rest,” he finally says after too heavy of a silence. “The trench-dwellers might not choose to stay at the old colony long term, and that’s fine. They just need to defend it. The corals and hybrids like Hitoshi will be enough.” He runs his thumb across the back of Hizashi’s hand, wondering if any of the survivors are among those that once swam alongside him in the colony. Of those that had traded their fins for feet as he did so long ago in the name of survival, the grand majority were little more than acquaintances. “You think your broadcast will work?”

“I’d like to think so! We may have lost contact with them over the years, but you can’t tell me the likes of some won’t take any chance to stick it back to humanity, so to speak, y’know?” He pulls Shouta’s hand up between them and presses his mouth to the mottled, half-shifted dark knuckles upon it. “I’ll bet you breakfast that those ones’ve been hoping for an opportunity for a century now. And we can finally give it to them, Shou.”

Shouta’s brows furrow. “And if they’re like me?” 

“Well,” Hizashi’s responding smile wavers as he replies a bit slower, “Then… I suppose we’ll see what kind of sacrifice they’re willing to make. If they come, it’s because they plan to help. That’s all we can ask.”

For a long few seconds, Shouta ponders this, unease slipping back into his heart. “Hizashi,” he starts, “If I end up going in… if I lose myself—”

He’s cut off by Hizashi shifting over to capture him in a kiss.

When the blonde pulls back, his gaze is glassy. “The possibility of it’s always been there, only a railing away, and we’ve been lucky for all these years, haven’t we?”

Shouta presses their foreheads together. He can feel every spike of Hizashi’s anticipatory grief as sharp as daggers against his heart. His eyes burn. He shares his agreement wordlessly through the stream of thought between them.

“And until it happens— if it happens—I’m going to look towards our future with a daughter, a son, and his mate, gathered all on a beach in Chichijima, smiling and singing and enjoying the sun .” Hizashi manages to flash a blinding, beautiful smile through the looming heartbreak; Shouta has never seen someone so strong. His mate’s kelp-green gaze softens. “And with the colony restored and protected, maybe you’ll finally have a chance to live in the present rather than the past.”

“It sounds nice,” he admits, memory boring a hole in his heart.

He remembers the music and lights; if he pictures them clearly, it’s almost as if the cabin room fills with them. Sun-glimmering scales in every hue, nights filled with laughter and song—he took the generosity, friendliness, and community of the corals for granted, once upon a time. Felt like he’d never fit in among them. And now, with decades of reflection trailing in his wake, he would give anything to have them back.

Though up until recently it’s only been a distant dream, a wish on the currents, he’s always known that restoring the colony would come at a price. But if the price of making that dream a reality for Hitoshi and Eri and all their future kin is to put himself on the front lines… well. That’s not an impossible cost. That’s a bargain.

Hizashi touches his face. 

“We can give them that future,” he says shakily, “all of them. But don’t you go throwing yourself overboard on me, you big fish.”

Shouta huffs against his mate’s lips. “You know I’m not one for irrational self-sacrifice,” he replies. Still, sensing that the blonde’s worry hasn’t abated, he chirrs from deep in his chest and flips Hizashi around—ignoring the indignant squawk—until the walker’s smooth, finless back is nestled snug up against his chest. 

He traces the lines of Hizashi’s tattoo and mark with his mouth and is rewarded with a shallow gasp and a barely-there shiver, the blonde’s hands moving to rest over his where it’s spread broadly across the pale skin of his mate’s collarbone. In the darkness of their cabin room, their limited magics brush and blend together—Hizashi’s affinity walker-erratic and untrained, his own muted and merely a shadow of what it used to be—simultaneously invisible to the eye but bright to the soul. 

And just like that, Shouta is complete. He doesn’t need fins to be whole, not these days; not with his mate pressed against him and a less bleak sense of forever waiting just beyond the horizon. Though they’ve only got hours to prepare before meeting with the Shinkai Maru ’s offered support, and what lies beyond that is muddied water, he plans to stay right where he is for as long as he can. 

He may as well. Their fates are caught in the currents, now.

Well into the dark hours of the evening, the Midnight Lady is moved. Over the entrance to the heart, specifically, where they’re met by several of the expedition ship’s smaller research vessels and nearly two dozen members of the Applied Magic research division. 

Despite how much he wants to meet them all, Denki has put off his tasks for as long as possible already today. So instead he grabs his tools and some of the questionable makeshift explosive device blueprints that Bakugou had scraped together and settles with his fellow mechanic close enough to overhear the discussions, but far enough not to draw attention to himself.

He glances up and doesn’t avert his gaze as one gray-haired researcher in a purple suit meanders closer to Aizawa with a curious grin, clearly eyeing the still-fading coloration on the ex-mer’s cheekbones and arms.

“This must be exhilarating for you and Yamada,” the stranger says with a laugh, until he, too, reads the lack of recognition on Aizawa’s face. “My bad—Yamada talked about you now and then, so I feel like I know ya! But I never introduced myself, did I? Okuta Kagero.”

“Aizawa Shouta,” Aizawa replies, shoulders hunched. “Thank you for your help.” It’s polite, but stiff.

Denki hums to himself; the name is familiar, but he can’t remember why. Had he sat in on one of the man’s talks in the early days of the expedition, during his breaks? It’s possible. He always did have a habit of gravitating towards magic and discussion of it. But the guy doesn’t look like the lecturing professor type in the slightest; maybe not.

“Happy to be here,” Okuta says with an easy smile, leaning back. “The director didn’t fill us in on all the details, but everyone with a lick of affinity on the pacific rim can tell that old ley-line down there is back in action. Can’t wait to get a good look at it myself!”

“Your help will be needed at the surface,” Aizawa counters. If he still had fins, Denki’s sure they’d be bristling.

Okuta waves a hand. “Sure, but afterwards. Though I don’t know if holding off other… interested parties for a day is gonna do any good in the long run; they’ll be back.” He side-eyes Aizawa, still smiling slightly. 

It’s then that Uraraka settling to his left catches Denki’s attention; she, too, is looking over at the pair of men with a curious expression. 

“D’you know who he is?” Denki asks her.

“Sort of,” she replies hesitantly. “I’ve certainly seen him around! He paid a lot of money to be on the expedition, but I don’t think he’s a researcher. More of an esteemed guest of the division than anything, I think!”

Well, that scratches out the possibility of the man lecturing, Denki supposes. His eyebrows draw together; Okuta Kagero . Where has he heard that before…?

“They trust him enough with the tech for someone who ain’t a researcher,” Bakugou grumbles. “He’s always getting them dented and shit.”

Recognition dawns in an instant, and Denki sits upright. “That’s—yeah! Jeez, I knew I’d seen his name! He’s the one who asked for the footage on my rover after we released Hitoshi!” He’d seen Hitoshi, most likely—no wonder Aizawa is on the defensive. 

Okuta pulls out a cigarette and lights it, gaze traversing the Midnight Lady and pausing on the three of them for a moment. He waves a hand in a casual wave which Denki and Uraraka return, then the man’s attention is back on Aizawa. 

“So pardon my bluntness, but I get the feeling that there’s more to this story than the director let on. What’s our plan for this showdown? What are we really doing?” 

“We’re fast-tracking documents to have the old merfolk colony grounds established as a protected area,” Aizawa says slowly, carefully. “We just need help defending it, and the ley-line, until the paperwork is cleared.”

Okuta shifts closer to him, lowering his voice until Denki and Bakugou both need to stop their tinkering to clearly hear. “Look, man, I wanna help you, happy to help you, but I’m no idiot. You’ve gotta give me something to work with. The ley-line isn’t gonna be long-term protected grounds just ‘cause it’s in the ruins of a ghost colony down there.” 

There’s a long, heavy moment of silence. Denki can clearly read hesitance on Aizawa’s posture even as he turns away, staring out at the water. Then, “Come on up,” the man calls.

What follows is a loud splash and the telltale double-thud of Hitoshi surging up out of the ocean. One handrail at a time, the purple mer muscles his way up the side of the boat until he’s staring Okuta in the eye, expression mostly neutral save for the unsure flick of his aurals.

Okuta, to his credit, doesn’t react with anything more than a short step back to give Hitoshi space. “Ah… so not a ghost colony after all,” he says. He blows smoke out to the side, sharply taking in everything about the fantastic being before him. “This is the one who took down my rover. I had a hunch.”

“My rover,” Denki mutters under his breath.

Okuta takes another huff, and this time moves closer, peering at the vibrant fins and eyeing the superb length of Hitoshi’s glistening purple tail, long enough that the end still drags in the water. “So, what’s its name, then?”

To Denki’s surprise, Hitoshi flares his fins and pulls back his lips slightly, baring the edges of those deadly teeth.

Okuta meanders backwards again, biting the edge of his cigarette and raising his hands in mock-surrender. “You can tell it to settle down, just never thought I’d see one in person. Forgive me a little curiosity.”

“Names are important to them, as you can see,” Aizawa explains, giving no attention to his adopted son’s display. “So that’s not something I can share.”

With a flick of his gaze between the pair, Okuta hums. “Real shame what happened to the rest of its folks. I’ve read all about that situation. One big mess, huh? And the laws, and the treaties. Too little too late! Yeah, real shame.” He blows more smoke to the side. “But I get the picture. The ley-line’s on colony grounds. The grounds are off limits so long as the treaty stands. And—” he points the cig at Hitoshi with a smile. “—the treaty stands so long as this one’s alive. I’m following, I get it. I do. But registering a colony takes time, and bodies. It’s got a fight on its hands ‘til then.”

Denki can see Aizawa reaching his limit in every aspect of his body language, knuckles clenched tightly around the handrails and jaw clenched. He wants to stand up and say something, if only to correct the pronouns and defend their goals, but—

“Don’t you worry about that, Okuta!” Yamada calls out, winking subtly at Denki as he passes and heads towards the other men. “We’ve got the numbers handled and the registration’s already underway. As for the fight, that’s why you’re here, yeah?” His tone is edged with cheeriness that borders on threatening. “Protection in return for a chance to study the ley-line’s magic when the colony’s re-established?”

Okuta snubs his cigarette on the railing before flicking it overboard with a lazy grin. “Of course, of course. Looking forward to it, naturally. And what better to fight magic with than magic, hm?”

Aizawa excuses himself, unsmiling, and walks away—but as he passes by, offers a hand to help Denki up and beckons to follow him. As soon as they’re out of sight, he huffs irritably. “It likely doesn’t need to be stated, but don’t tell them anything more than what they need to know,” he murmurs. “Nothing about Eri. They may be on our side, but they’re still thieves all the same.”

Denki swallows, staring at his feet and trying not to let the lingering guilt show too clearly as he nods.

Apparently it doesn’t work. Aizawa notices and sighs, squeezing Denki’s shoulder gently. “You’ve paid your dues for your old ways, kid. You’re not one of them.” He clears his throat. “And we’re lucky to have you on our side.”

Pleasantly stunned, Denki is slow to really process the compliment, and this time he isn’t a teary, blubbery mess. The guilt is swept away in an instant, replaced with an all-encompassing warmth, because that’s high praise from the crotchety old siren and both of them know it. The next thing he knows he’s beaming and stammering for some return compliment, but none of it makes much sense while his head is so filled with sunshine and relief.

Aizawa huffs amusedly despite his eye roll, but doesn’t protest the sudden hug that Denki apparently asked for and acted on without thinking. There’s something calming about the hand that momentarily settles on his head until he’s well and done invading the man’s personal space. Then Aizawa gently pushes him back, turning away with a barely-there smile.

“No more goofing around. It’ll be dark soon; go get ready and meet us at the pool,” he mutters, the chastisement weak. Then he’s gone.

‘Getting ready’, to Denki’s ongoing concern, means gearing up in his full wetsuit and inflatable lifejacket despite having no intentions of going in the frigid Atlantic water. He carefully secures a few of his makeshift explosives within easy reach; they’re not enough to do any significant damage, but the noise and shock value might come in handy. They remind him of the kind of magical party tricks he could pull off before his accident; mostly for fun.

When he arrives at the meeting, however, he’s taken aback to find actual weapons readied for them – some crossbows, hatchets, and that frighteningly legitimate arcane cannon that Bakugou had apparently dragged up from the colony grounds. Even Uraraka is cautiously studying something that Denki’s pretty sure is an actual trident. 

Suddenly, faced with the reality of the weapons, all sense of ‘fun’ bleeds away with the rapidly-setting sun.

This is happening.

“With any luck, this all won’t be necessary, listener,” Yamada says loudly, coming up behind Denki with a slightly-too-hard shoulder pat. He’s got a powered-off loudspeaker swinging from his other hand. “But it’s good to be ready, ya get me? I’ll be running the comms again and keeping an eye on things. Unless there’s a really good reason to get in the water, don’t. No doubt at least one poacher vessel will be hauling sonar equipment.”

It’s Bakugou who pauses at that, raising his critical red gaze. “You think they’re gonna have something military-grade?” He glances at Hitoshi. “That’d be…”

The unfinished sentence hangs between all of them.

Denki’s no stranger to how sound travels underwater; deafening, reaching on seemingly forever, enough that the vibrations can shake your insides apart if you’re in the wrong situation. Even for the Shinkai Maru’s less powerful research-grade sonar equipment, there were always protocols to follow to ensure no local marine life was severely impacted. No beached whales, no irreparably disrupted patterns. Even divers in the water nearby would be extremely careful to avoid ruptured eardrums and other vibration-related traumas.

A ping from military-grade sonar would be lethal.

“It would be extremely bad,” Yamada finishes a bit weakly. “But also self-sabotaging their own divers.”

“Greed has pushed people to worse,” Aizawa mutters as he looks down at Eri, cradled in one arm. His other hand bears a crossbow. “Just keep it in mind.”

They all nod.

Uraraka sets up a small first aid station of sorts, saying not for the first time that they probably won’t need it but it’s good to be safe. Bakugou’s making no such claims, testing the repurposed cannon with his own limited affinity for magic and turning heads when a loud boom resounds across the open water. He smirks in the face of Aizawa’s chastisement and Hitoshi’s clear annoyance, proclaiming they’d be glad he made sure it works when it comes time to use it later.

Denki, still somewhat lost as to his own role, is gathering supplies to keep crafting various little utility devices when Aizawa calls for him. The man is waiting by the repurposed Jacuzzi with Nemuri and Hitoshi, the latter now once again holding Eri’s small form. It seems like they’d been in discussion about him, as all three sets of eyes track him as he slowly makes his way over. 

While none of the three have ever given him good reason to fear them, there’s something different about the actions of the three mer when they’re amongst only themselves, Denki thinks. It’s as if having humans around tempers their body language, forces them to adapt to movements and gestures that bridge the gap of racial normalcies. But now, as Denki approaches with his gaze flicking between the trio of Chaos-born beings, uncanny valley comes to mind. On their own, the three are inexplicably intense and still and attentive, and some primal part of him recognizes the Other within these predators and it very nearly freezes him in his tracks.

Aizawa seems to recognize this first. He shifts his weight, blinks, and looks at Nemuri—and just like that, the unvoiced spell is broken. The woman runs a hand back through her hair and laughs under her breath, and even Hitoshi, less accustomed to adapting, slides further out of the pool as he chirrs for Denki to come closer.

So he does, taking a deep breath to clear the remaining nervous bubbles in his chest before looking up questioningly at the one who’d summoned him. 

Aizawa tilts his head slightly. “Are you prepared?”

Denki swallows, his nod hesitant. “As prepared as I’m going to be, I think? Where should I be?”

The man and Hitoshi share a momentary look.  

“You’ll be right here,” Aizawa says after a moment. “With Eri.”

It takes him a few seconds to realize he hadn’t misheard that, and neither of the others are correcting Aizawa on it. He’s shaking his head even before he can find the words, lamely offering a croaked, “Oh no, gods, I can’t be responsible for—” 

“Do you trust us?” Aizawa interrupts, unwavering.

Denki pauses in his protest, stunned. “Yeah, of course,” he answers quietly. “But—”

“—And we trust you,” Nemuri continues for him. “We know you’ll do whatever it takes to protect our little girl.” 

Aizawa nods. “This way we’ll keep attention off her without leaving her unattended. You’re the best option for this, kid. Besides, you have just as much drive to keep her safe as any of us. You’ll manage just fine.”

Wordless, Denki stares at one, then the next, then the next. He can’t do anything more than offer his arms when Aizawa lifts the sleeping girl from Hitoshi’s hold and hands her to him, delicate like sea-glass. He looks down at her, the weight of the situation impossibly heavy.

Nemuri chuckles. “You look so rattled , sweetheart, what is it?” 

“It’s just…” he swallows. “…she’s… she’s your future.”

A tail-fin gently thwaps the back of Denki’s legs, chastising, startling him into looking down at Hitoshi. 

“Denki,” the siren says with a small, confident smile, “our future.” 

It’s enough to make Denki suck in a breath, because despite the fight looming he can start to properly picture them making this work for real, and while he can’t quite make out the details just yet they’re so close .

A horn sounds from elsewhere on the Midnight Lady , and when it ceases, the unmistakable voices of Yamada and Bakugou are calling out about boats sighted to the northwest. Denki’s heart plummets like it’s been weighted down with rocks and a vile mix of anxiety and adrenaline viciously twists through him, and he sits down abruptly at the pool’s edge, wishing he could hide, or do something, they just needed a bit more time—

Everyone starts to mobilize around him, and in that moment he realizes the calm before the storm has truly come and gone.

But Hitoshi grabs his leg, and more insistently murmurs, “Denki.” The siren’s usual languid behaviour is nowhere to be seen, as if he’s determined to make sure they’re on the same page. 

Denki sinks into the pool and kisses him, ignoring the fear-racing of his pulse. “Our future,” he repeats breathlessly. 

Still, the moment is interrupted by Aizawa, whose voice is steady and strong despite the rush of both companions and Applied Magic students and instructors taking up position behind him. “If we’re going to catch them by surprise, he needs to get in the water,” he points out, to which Hitoshi nods. 

The realization that Hitoshi is leaving catches Denki in a panic. “Can’t we just show him, to prove it’s a protected zone?” 

Aizawa levels with him; “It’s only protected if he’s alive. And I wouldn’t trust the poachers for a second to spare one or two mer when the strongest source of magic in the Pacific is at stake. There would be blood in the water the moment he shows himself – all of ours.” 

Dread seizes him. He turns to Hitoshi, but the siren looks just as unwavering as his new dad. 

He starts to say a bid for safety but Hitoshi cuts him off with another kiss, then touches his head to Eri’s—and finally the siren gracefully slips away, disappearing with a small splash over the port side of the boat.

Denki is left staring after him with Aizawa, until the man murmurs, “Keep your head low and try not to draw any attention,” and moves ahead slightly, just enough to put himself between the pool and the group gathered on the starboard side. Beyond, several smaller boats are rapidly approaching.

It takes several more minutes of tense waiting before Denki can make out the sounds of several distinct engines, and one or two more before those engines are one by one switched to idling. From where he sits in the pool, only his head visible but even then partially hidden behind chairs and railings, he can see dozens of boats drifting in the open water. They’re far enough that there’s no chance of being boarded, but close enough that even through the dim light he can make out the smug expression of the man stepping forward on the closest boat. Denki stills in place, afraid to even breathe as the poacher meets Yamada’s too-casual, posturingly-widened stance with one of his own.

“Well, hello there!” Yamada calls out, Okuta at his side. “What brings you to the expedition site at such a late hour? Don’t think the director was expecting any guests!”

The lead poacher lets out a hoarse laugh. “Guests? Nahh, I s’pose the only invitation was from the sea itself. Nice evening for a little dive, don’t ya think?”

“Not here, I’m afraid. These are protected grounds, you see!” Despite the enthusiasm in the blonde researcher’s voice, it’s underlined with steel. “There’s a conservation project underway and the colony grounds around the ley-line are off-limits. I’m sorry that you came all this way for nothing!”

“Don’t worry,” the hunter says, sneering slightly. “We’ll be extra careful not to crumble any dilapidated ruins on our way down.”

It’s then that Okuta steps forward, to Denki’s surprise, and equally easy grin on his own features. He waves a hand dismissively, every part the relaxed, nonchalant speaker he’d been earlier. “You’re misunderstanding him, boys,” he drawls, before pulling out another cigarette. “There’s living mer about. Swear it on my magic.” Then he brushes his fingers together and ignites the tip of his pointer with a tiny flame to light the cig. 

That, if nothing else, makes the poachers falter. They trade looks amongst themselves, before their designated spokesperson tilts his head up slightly. “There’s no registered colony here anymore. Died out ages ago.”

“Even checked before we left,” someone on another boat calls out. “What are you lyin’ for?”

Yamada shifts his weight, propping his hands on his waist. Through a grit-teeth smile, he says, “Paperwork’s slow! You know how it can be, yeah? Give it a day.”

Denki’s heart pounds away in his ribcage. He can hear more boats arriving and shutting off their motors; there must be far more than the dozen Nemuri had predicted. On the few he can see, several of the men and women on the decks are gearing up to go overboard, listening into the stand-off with interest. 

The spokesperson hunter scoffs; the pleasantries are dispersing faster than blood in the water. “’Give it a day?’ You’ll have it tapped dry by then, blondie, don’t think I can’t feel the magic bleeding from your boat. You just want it all for your gods-damned selves.” He chuckles as if Yamada’s made a joke, turns to his near-armada of vessels, and calls out, “Are we gonna give it a day, friends?” 

He’s met with a verifiable roar of laughter and disagreement that echoes over the open ocean.

Denki tucks Eri closer to his side. He sees the line of Aizawa’s spine tensing, can practically feel the animosity surrounding the ex-siren like a palpable cloud. Diplomacy didn’t work. It didn’t work.

The poacher turns back to Yamada, his mocking smile ice-bright. “Well. There you’ve got it. You’ll have to take it up with each of them.”

“Actually,” Yamada says. “ You’ll need to take it up with the locals.”

Several on the other boats pause at that, but their leader scoffs and motions for some of the divers to continue. A few keep buckling their gear, pulling on masks and harnesses and tanks. There’s one or two isolated splashes outside of Denki’s range of vision.

But then the Song begins.

Hitoshi’s voice rings clear across the open air, layered with magic and intent.  It’s odd being on the other side of it for once, untargeted by whatever commands Hitoshi’s issuing that don’t translate into orders in the deeper parts of Denki’s brain. Still, it’s not hard to figure out what’s being asked of the divers, as they drunkenly fumble to remove their gear as if caught in a daze.

It seems that Hitoshi can’t catch all of them, however, and it’s not long before the shouting begins.

“Where is it? Where’s that coming from?!”

“Stop that blasted singing, whatever it takes!”

It’s almost laughable, seeing them scramble in the face of Hitoshi’s power, but Denki’s brief amusement is shattered the moment he sees someone pull out a harpoon gun. Fear floods his stomach, catches him by the throat. Suddenly he realizes that he doesn’t even know where his siren is, and his position is a poor vantage point.

“Last chance,” Yamada calls out from his high perch, swinging an arm out theatrically with a clench-jawed smile. A sheen of sweat borders the older blonde’s face, highlighting the tightness at the corner of his eyes, even as his gaze is hidden by a pair of triangular orange shades. Unlike his mate, Yamada lives with his heart on his sleeve. He must see the harpoon, too. 

But surely it’s a ruse. They wouldn’t actually—

“There!” someone among the poachers cries, followed by whistling air and a heavy thud that jolts the Midnight Lady.

Hitoshi’s Song cuts out, Denki’s heart stops, and the world goes to hell.

Hitoshi’s name claws its way up Denki’s throat and into the air, sharp and jagged and desperate. He lurches to leave the pool so he can see if the siren is okay, if he’s alive, but Aizawa intercepts him with a kneel and snags his free arm around Denki’s torso. He’s pulled back, struggling, then turned away and held against the ex-siren’s broad chest, his back to the chaos. 

“Missed—they missed him,” the man hisses, not far from his ear. His voice, though low, shakes with unmistakable rage. He sucks in a deep breath and urgently encourages Denki to do the same. It’s more of a restraint than an embrace, but for what just took place, it’s enough to steady him.

But the shouting grows louder, and Denki feels numb. They’re actually fighting . It was one thing to talk about it, to see the weapons and understand their purpose, but something entirely different to comprehend that someone just shot at Hitoshi . Like a wild animal, like a dumb fish, with intention to kill.

He chokes out, “Can’t let him die,” one hand tightening in the towel around Eri and the other catching Aizawa’s arm in a vice-grip.

“He won’t die. He’s far cleverer than a bunch of rasyakiin . But you need to stay out of sight, kid, do you understand?” 

Aizawa’s tone has an undercurrent of pleading, making Denki realize just how close he’d come to jeopardizing his one real task—protecting Eri. He takes another steadying breath and nods, adjusting the towel around her. “Sorry,” he murmurs a bit shakily.

The ex-siren releases him and watches him get back into the pool. “I won’t let anything happen to my pod,” he replies. “Which includes you . So stay here and yell if you need anything.” Red lightning flashes in his gaze. “I have boats to sink.”

Denki nods again, throat tight, and watches him load the crossbow as he leaves.

Though the sun is gone and night has set in, it’s anything but dark. Even the moonlight is outshined by bright flashes and streams of magic from sources far outside Denki’s view. As they arc and jettison through the night sky from both directions, he tries to pick out specific voices and sounds in the fray; the boom from Bakugou’s cannon, Yamada calling out target threats, the roar of seadoos circling the boat. He can see ribbons of magic aimed at the upper floors of the Midnight Lady, but they hit what seems to be an invisible domed barrier over it and disperse with little more than a flash and flicker. 

The updates over the radio sitting at the edge of the pool are sparse. After what seems like hours and hours but might not be more than one, Uraraka comes for him. She’s limping slightly.

“You’re hurt,” Denki says, guilt eating away at him. He’s sitting here, tinkering with what might as well be toys and playing the babysitter, and even she is out there helping.

“Just slipped is all,” she replies breathlessly. “It’s nothing! We’re holding up pretty well, actually. The boat’s a bit of a fortress with all of Nemuri’s artifacts. The cannon might not last much longer, but – well, you and I both know Bakugou’s never been one for restraint or moderation.” Uraraka laughs weakly, casting her gaze over his assortment of tools. “He’s going to burn out his affinity soon. Are those done?”

Denki holds out a few of the small makeshift explosives. “They’re not as strong as he’ll probably like, but they’re done as they’re gonna get.” He hesitates. “About the backup...”

She shakes her head apologetically. “It’s… hard to see anything below the surface, but Hitoshi’s the only mer out there Singing right now, I think. It might’ve been too little notice for the others. And there’s been nothing from Professor Yamada’s distress call yet.”

He hums acknowledgement. It’s not promising and they both know it. He can see his unspoken worry mirrored in Uraraka’s quick, stiff movements as she carefully gathers his offerings. Just how long can we hold out…?

A war of attrition is a grim prospect, given the circumstances.

She thanks him and takes off again, and Denki is left to his own devices once more. 

He’s got two contact explosives left, another unfinished, plus one questionable taser that will no doubt be single-use, if it works at all. It’s difficult to stay focused on them, but he forces himself to do so, if only because he’s not sure his nerves will hold up if he keeps giving too much attention to the sounds and sights lighting up the night. The fact that none of the others have given him updates—and the radios have gone mostly silent—is not a promising one. It means their focus must be elsewhere, tied up.

He wishes he could be more help.

Denki’s weighing the pros and cons of requesting an update himself when the stern dips a bit and he hears someone pulling themselves from the water. Hitoshi, his hope supplies, until the barely-lit individual gets their feet under them and rises from a kneel with a grunt, dripping where they stand. 

Unsure of whether to shout for help or hide, Denki sinks further into the pool, unable to take his eyes off the newcomer.

But, “S’alright,” the man calls out, his voice is gravelly and smoke-rough—oh. The figure wheezes slightly, coughing up water. “Just me. Okuta. Gotta catch my breath.”

Denki swallows back his fear, relaxing a fraction. “You ended up in the water?” As Okuta staggers forward, pulling his glasses from a breast pocket and easing them on, Denki notes—with jealousy—the glimmer of magic the man wears like a suit. Maybe some sort of warming or quick-drying enchantment. Summer or not, that ocean is cold. “What’s happening? Are we losing?”

“Well. I wouldn’t say we’re winning.” Okuta heaves a sigh. “This…. ‘defense’? It’s not gonna last long. Your friends might not want to admit it, but—” he waves a hand around as another boom sounds. “—this ain’t sustainable. We’re running out of juice. Best to pack up and let ‘em have at it before someone gets hurt.”

Denki shakes his head. “We can’t do that.” He unconsciously shifts Eri in his grip, holding her closer to his chest.

He realizes his mistake too late. 

The action draws Okuta’s gaze, and Denki can see the moment the man registers her, his silhouette against the inconsistently-lit night sky going perfectly still.

“Nobody mentioned anything about a little mer kid,” the man murmurs. His tone is hard to read, and his face hard to see, but his focus on Eri is clear. It doesn’t seem like the now-typical awed, reverent focus, either. He pulls out a new cigarette – miraculously dry – and ambles closer while he lights it, stare never leaving her.

“Sh-she’s asleep,” Denki explains quickly, fighting the urge to angle his body away. Aizawa hadn’t trusted the man, and maybe that’s why his internal alarm bells are now ringing, but he balances it against the justification that Okuta’s only helped them so far. “And she’s so little, she can’t fight, y’know? So I’m—I’m just looking after her. Best to stick the two of us together, out of everyone else’s way—”

“Right, right,” Okuta says agreeably. The faint light from his cigarette catches his glance up at Denki, short but re-evaluating in nature. 

It doesn’t help the uneasy prickle climbing the back of Denki’s neck. After a few moments of tense quiet, he finally forces out, “Was there anything y-you, uh, needed from me?”

“Depends!” The man crouches at the side of the Jacuzzi. “I’m runnin’ low, same as everyone else, I suspect. Got any magic to spare, kid?”

“I—no, um. Sorry. All out.” It’s not entirely untrue.

Okuta dips his head. “Hn.” His pink-red gaze has returned to Eri. “Does… she? Feels like it’s— she’s got a lot of energy. More than she’ll need sitting back here.”

Invisible fingers of anxiety brush their way around Denki’s neck, tapping along his throat. He shakes his head, the rest of his words locked in a place of fear. They may be on our side, but they’re thieves all the same.

But as the memory passes by, Okuta rolls his shoulders back and angles himself away, finally breaking the stare to puff out smoke in the other direction. “Relax! Relax. Just… curious. It’s all new to me. Real interesting stuff.” He takes another long, slow draw. “You’re one of the mechanics, aren’t ya? And here you are, all tangled up in this. How much d’you know about the area? What’s it all look like down there?”

Try as he might, Denki’s heart won’t stop pounding, along with a tightness in his chest that tells him he needs to abort this conversation now. “Uh, not m-much,” he admits nervously. He reaches for his radio. “But I know someone you could—” 

Okuta surges forward in an instant, slapping the radio into the pool with a small splash and blowing smoke into Denki’s face.

It smells sweet. It’s all he can focus on for a moment, as if someone had taken a broom to his thoughts and swept them all aside into a terribly unimportant jumble, muddying his thoughts.

But then his face hits cool water, and he feels the hand on the back of his head holding him there—and he can’t breathe.

He thrashes as soon as the realization hits, trying and failing to fling himself back enough, ice curdling in his veins. The familiar weight on his lap has slipped, and it takes him a moment to remember what it is. Eri, he thinks, struggling against the bruising grip and trying to pull her back to him. But the angle and his lack of mobility pose their own issues; his directions are limited. 

So instead of up, he sinks himself down, and tosses one of his little explosives blindly over his shoulder.

The percussive force shudders through him beneath the water. Okuta hasn’t let him go entirely—he must’ve missed—but the man’s grip loosens just enough. Denki bodily throws himself to the other side of the pool and wheezes for air the moment it’s available, ignoring the ache of his scalp.

It’s still dark, so damn dark, not helped by how the recycled sea water is stinging his eyes and nose. Denki can’t call out for all his wretched coughing, even as between rapid blinks he sees Okuta lunging through the pool at him, no doubt aiming to finish what he’d started.

“Please —” Denki gasps—

—And recoils when another shape slams into the man’s side, sending both forms crashing heavily to the deck. 

Aizawa. He’s little more than a malevolent shadow in the night, his rage almost a physical force despite his silence as he pins Okuta’s to the deck and starts pummeling the other man’s head and chest. It isn’t until Okuta catches him in the back of the thigh with a small knife Denki’d only seen at the last moment that Aizawa makes any noise at all. His snarl and hisses of pain are entirely siren, ratcheting up in intensity as the knife is freed and sinks back in several more times, the only location Okuta can apparently reach. 

Spell-light from the battle beyond them illuminates the wetness coursing down Okuta’s face. Blood from his broken nose paints his teeth in harrowing red as he grins up at the furious ex-siren looming over him. “Always figured there was somethin’ inhuman about you.” He bashes the damaged leg, earning another sharp grunt from Aizawa that lets Okuta worm himself free. He whistles sharply, a few short notes.

Denki finally finds his radio, but its unplanned bath leaves it crackling; he’s pretty sure his calls for help don’t go through. But he spots Aizawa’s crossbow, presumably discarded on the ground from the moment the man had tackled Okuta, and snags it for himself.

There’s a single shot loaded. He aims and fires; it hits the far railing and ricochets into the water.

It does, however, catch both of their attention. Okuta lets out a single mocking laugh and lifts his chin in a sneer, but before he can get out whatever poisonous words wait on his tongue, there’s another sharp clack from above, and the man stumbles back—with a bolt sunk into his left arm.  

Yamada leans over the upper deck, hair astray from its tie and eyes wild with hate. He stares down the length of his own crossbow and starts loading another shot.

A sea-doo with two other hunters pulls up at the stern. “Giran! Get on!”

Okuta—or ‘Giran’, apparently—nods to them and backs towards the edge. “The fish child,” he rasps sharply, staggering onto the rear of the vehicle and sitting down hard. “Capture it.”

The hunter in front of him nods and twists her hands in a looping, tying motion; from her glowing palms shoot twin lasso-like ropes of magic, amber-hued and bright. Denki doesn’t have time for awe, as within a blink they’re lashing towards him and snagging precisely around Eri’s torso and tail.

He curls himself around her just in time. The first tug pulls frighteningly hard. With her body tight to his chest, he can hear the air being forced from her lungs, and in response he tangles his hand in that rope and pulls back so that the constriction lessens a fraction. It doesn’t, however, stop him from being dragged several feet out of the pool and towards the stern. 

“Keep going,” he distantly hears Giran order. “Drag the cripple in too. He won’t be a problem in the water.”

Denki slides another involuntary foot across the deck, terror flooding through his veins and gathering in his heart. The next foot brings him in contact with one of the fixed chairs of the deck, and he desperately attempts to anchor his feet on it, ignoring the pain lancing up his legs and pulling at his knees. He won’t let go. He can’t. So if pain’s what it takes—

Yamada’s second bolt whistles through the air above him and finds its mark, according to the resulting cry; the ropes fizzle into nothingness.

Denki tilts his head back, staring across the stretch of open deck at Giran. His breath catches when he finds the man looking right back at him, hardness in his gaze—but also apology. 

Without averting his stare, Giran raises a hand, summoning his own arcane rope.

“It ain’t anything personal, boy,” he says, and flicks his hand to send the rope forward.

Denki flinches and curls tighter in anticipation—but it never reaches him.

Something solid hits the floor between him and the stern, letting out a low hiss of pain. Hitoshi, Denki thinks, but when he looks up it’s not the younger siren’s form curved defensively in front of him. 

It’s Aizawa. There’s a lasso of light wrapped firmly around the man’s legs, biting into the earlier wound and spilling red across the deck. The dark-haired ex-mer clenches his teeth and grabs at the solid magic, but it doesn’t budge.

“Always in the way, ” Giran growls—and reaches for his companion’s weapon. 

Denki doesn’t stop to doubt himself; he wrestles the last of his finished explosives free, pulls the safety, and flings it towards the sea-doo. Though he can’t see where it lands, the clatter suggests it has gone into a rear foot-well – further supported by the surprised cursing and immediate scramble.

The muffled bang sounds like victory. Until it isn’t.

“Go—go! Before we sink, you idiot—”

An engine revs, strained, but all sense of relief is drowned out by a tense, quiet, “Shit,” only feet from his face. “Shit.”

The rope, Denki realizes distantly, the thought like an echo. The rope is still on Aizawa.

He hears the smoking sea-doo kick into gear. 

He sees the moment Aizawa must realize that fumbling against the hunter’s magic just isn’t working; after a timeless pause, the trapped ex-siren rolls in spot to stare wide-eyed, past Denki, towards the railings of the upper deck.

Denki feels the wordless apology written in Aizawa’s features as clearly as if it were his own, and watches it fold into terrible, visceral grief.

For a moment that pained gaze meets Denki’s, then flicks down to Eri, still cradled in his arms. “Keep them safe,” the man says roughly, reaching out to touch his royal’s cheek.

The rope goes taut. 

With one last glance skywards, Aizawa is dragged into the sea.

Chapter Text

Denki’s shock breaks at the anguished wail that cuts sharply through the air. It draws out into a desperate, choking sob, and is followed by the clatter of a crossbow falling over the upper deck railing from hands limp with grief.

He moves for the stairs, re-bundling Eri in his arms, but the unsteady throbbing in his legs prevents him from making the climb. Even then, there seems to be no need to rush. Yamada isn’t moving. The man simply stares at the spot where his century-long partner disappeared in the wake of the sea-doo, his defiant and determined body language visibly fracturing as Denki watches.

Yamada sucks in a short breath that rolls into another sob. “He’s gone,” he says, distant and frighteningly soft. “He’s gone.”

Gone? Sure, he was dragged in, but even from here Denki can see that the rope of magic from the fleeing vessel has already faded. He waits, but Aizawa doesn’t surface. “He… he can swim, right? Even with his legs?” Denki asks. He knows, deep down, that he’s never seen the man do so. When in his right mind, Aizawa always seemed to avoid the water like the plague. When not…  

Denki remembers the incident the morning of Eri’s creation. How desperately the others had restrained the ex-siren from throwing himself overboard, the lengths they’d gone to keep him away from the water. As if it were something terrible and too final. 

An inability to swim suddenly sounds silly and unlikely.

Splashing from the side of the boat has Denki glancing over, grasping for hope. It’s not Aizawa, but seeing the vivid purple mer brings its own form of relief. 

Hitoshi pull himself aboard, rapidly followed by Nemuri, who is almost entirely midnight blue and barely visible in the darkness as she staggers to her feet.

“Hizashi?” she calls out, her pitch edging higher with alarm.

Above, Yamada answers with another full-body sob.

It’s enough to draw both of their attention. Denki steps aside and Nemuri rushes past him wordlessly.

Denki turns to Hitoshi. When the siren looks back at him, unfocused and with aurals pinned fear-low, there’s no doubt in his mind that Hitoshi already knows. 

The pod bond. A mental link. Denki wonders what that would feel like, right now. Is Aizawa changed somehow? Can they still sense him? Is he dead? He has so many questions, needs to know what it means for the grumbly, dark-haired pod-sire as well as the rest of them, but can’t bring himself to ask outright.

“Where would he go?” he asks instead, glancing at the stairs as Nemuri leads her old friend down to the main floor of the deck.

The sea witch and researcher share a long look. Yamada’s features pinch with pain.

“Likely towards where he can best feel Oboro,” the man says weakly. “Shouta never forgave himself for his death. He told me once that the souls of the royal mer never quite disappear… they fold back into Chaos. They’re made of it, through and through.” He exhales shakily, gaze sliding to the bundle in Denki’s arms. “If Eri is here, and his instincts have reverted, he’ll go to the next best place. He’ll go to the Heart.”

“He’s still got legs,” Denki points out. “We can catch up.”

 Nemuri peers at him. “You want to go to the Heart? Now?”

She flicks her gaze out over the water, and Denki’s follows. It’s dark. It’s cold. Even in a best case scenario, the communication lines wouldn’t be open like they were last time. And if anything went wrong… 

Denki chews on his lip, thinking it over before answering. “It’s the safest place for Eri at this point, isn’t it?” He shuffles her weight, feeling the strain in his arms but resolutely ignoring it. “We can’t defend the boat. We thought we could, but we can’t. That much I’m now sure of. The hunters have the advantage on the surface. And that guy—he knows about Eri now, so it won’t be long ‘til he comes back. I know we didn’t want to lead them to the ley-line, but… it’ll be the easiest place to defend.” 

Yamada is quiet for a moment. “I can lead them away, if they think Eri’s still onboard here.” He nods, mostly to himself. “Nem, you go with them.” 

“Hizashi—” 

“The kiddo is right. It’s our best option.” His smile looks pieced together with glass, and there’s distance in his eyes. “I’ll be alright. I think—I think he knew this was coming. I’ll make peace with it. Go on. I’ll… get back on the comms as much as I can, and move the boat.”

Nemuri seems content to back off at that, but Denki is not.

He waits until he has Yamada’s gaze before asking, “If we do find him?”

Yamada squeezes his shoulder before turning away. “Pray that he's still in there.” 

Denki thanks the foresight Uraraka had about getting him into his dive suit; all he needs to do is attach his mask and tank. When they’re ready to go, Yamada isn’t there to wave them off. 

“We’ll need to move fast,” Nemuri says, tying back her hair and glancing out between the hunters’ vessels. “As much as I regret to say it, I can’t keep up with these legs of mine. I’ll take the hand propeller. Guppy, can you carry these two?” She indicates to Denki and Eri, the latter of whom now rests in a makeshift sling across his front.

Hitoshi flares his aurals without hesitation.

Denki doesn’t question it, doesn’t let his anxiety take the time to build. But as he moves to the stern, for the first time he can clearly see the ongoing fight spread across the nearby waters. It’s hard to make sense of it all, or to figure out who is on which side. There must be at least thirty boats that he can make out the shapes of in the dim moonlight, firing on each other and often hitting. He sees that several of them seem unmanned, as if their owners have gone overboard—willing or not.

But he doesn’t have time to dwell on it, and on Nemuri’s prompting, gets in the water himself. Without further ado, he settles into the pair of purple arms, nods his readiness, and they leave the Midnight Lady behind.

The ocean is like liquid ink. If it weren’t for the light of the propeller and the enchantments on his visor, Denki’s sure he wouldn’t be able to see more than scant inches away from his face. In the interest of speed, Hitoshi’s swimming above him with his arms like vices around Denki’s torso. Which is fine— except it means that when Denki looks down or really anywhere else apart from the surface, all he sees is the endless void.

This goes on for several more minutes, by Denki’s estimation, as he tries to remember just how long it’d taken them last time to reach the barrier—and how long this quicker travelling method is shaving off. In fact, he’s about to ask roughly how far they are when a resounding boom echoes through the waters, jarring his teeth. Something directly ahead of them fractures with light like cracks rapidly spreading across an icy surface.

“What—?” he starts, only to be cut off by a low growl from Hitoshi.

Nemuri says, in nearly a whisper, “It seems they’ve found a way to breach the barrier, sweethearts.”

They move closer, then abruptly freeze, and Denki realizes that’s not the half of it. The light from the fissure in the barrier illuminates a scene before them. He narrows his eyes, spotting a trio of figures near the fracture who seem to be… fighting. Two appear to be wearing diving gear. The third does not.

“No,” Nemuri hisses.

Charcoal-colored skin that Denki had mistaken for a diving suit. Wild, drifting black curls. A deep, guttural snarl as the figure lunges for one of the others, jaws-first.

Denki gasps. “Aiz—”

Hitoshi stiffens behind him and quickly clamps a webbed hand over the speaker for Denki’s mask, and Denki realizes why too late.

There’s a spray of bubbles that burst towards the surface as Aizawa shreds the gear of one diver with his teeth and goes back for more. The man’s shrieks of terror carry easily across the scant dozen feet of salt water, and he’s struggling to fight, even as a growing cloud of red discolors the light and paints the scene in a more horrific reality than Denki could have imagined. As the flailing diver chokes and tries futilely to free himself, their interlocked rotation brings Aizawa’s face into view.

The vivid, glowing crimson irises and feral snarls amidst the blood render him entirely unfamiliar.

There’s a reason the sirens who lurk in the deep sea have been called man-killers throughout history, Denki knows. The stories of them are as old as human memory. In fairy-tales and myths and textbooks, just like the rest of the mer.

And now, equally as real. 

He can tell the others must be just as shocked, because it isn’t until Aizawa abandons the limp, now-silent body of the first diver and beelines for the fleeing second one that Nemuri kicks into gear and turns to intercept. 

She slams into him, tangling herself with his still-humanoid limbs and repeating phrase after phrase of insistent-sounding Mermish that seems to be about effective at dissuading him as blowing bubbles. When Aizawa attempts to lunge again at the second diver and finds himself held back, he turns his nails and teeth on Nemuri with a roar. The scores of red lines he leaves down her blue-mottled back earn him a furious screech that make Denki’s stomach turn.

Nemuri hisses, and knees him in the injured thigh before slipping into tongues. The strange pink hue of her sleeping magic permeates the water, and Hitoshi glides back to stay out of its path—

But it doesn’t work. Aizawa throws her off, turns, and darts into the darkness.

“He’s so far gone,” Nemuri says, the sounds as close to Japanese as she can manage while relying on gills. “I—can’t leave him like this. They’re supposed to face walker laws, not…” she nods towards the first victim, letting the implication do its job. “I need to go after him, dear. Keep going. Wait this out at the Heart.”

And after pushing the propeller into Denki’s hands, she, too, is gone.

The trip down through the vertical stone corridor to the Heart isn’t nearly as eventful as last time, which is good, because Denki’s earlier attempts to stave off further anxiety are all but wasted now. He stomps down his panic as Hitoshi navigates them around the U-bend at the deepest part and upwards again, and it’s only when he starts to feel the proximity magic humming all around him that he lets himself believe they’re safe.

Relatively. Maybe.

He pulls himself and Eri out of the water and onto the flat section of rock where he’d laid recovering during their first trip down. The Heart chases away his chills with ease but doesn’t do much for the shaken feeling. He leans against the wall with Eri in his lap near where his and Hitoshi’s stones are embedded firmly and glimmering in the pearly chamber wall.

“Well, you did promise we’d be back,” he says once he finds a moment to gather his wits. “I gotta say though, buddy, this isn’t quite the situation I’d expected. Heh.” 

Hitoshi makes no attempt to reply.

In fact, he refuses to relax. No matter what Denki says to get him to join them, the siren stays half-submerged in the water, staring transfixed at the entrance to the Heart with all signs pointing to aggression. 

It’s disheartening and more than a little stressful even to watch, so Denki makes a point of Not Doing That. He shifts so he’s not looking directly at the siren and instead busies himself with finger-combing out some of the wet tangles in Eri’s gravity-defying hair. The weight of her is reassuring. It’s a good remedy to the shaking of his hands, too. 

“Funny how such a little being like you can make such massive waves,” he says, if only to hear something other than the soft lapping of water. “Waves. Get it? Because you’re— yeah, you know what, that was bad. The last thing you should have to hear when waking up is one of my jokes. Though we all could use a bit of humour right now, if you ask me.” 

He lifts another section and begins to untangle it, idly studying a large, sky-blue embedded gemstone nearby. It looks like a cloud, part of a quartet with smaller black, golden, and navy gems. Then he continues.

“I don’t know how much you’re absorbing while asleep, or what you’ll remember—especially if you’re the embodiment of, uh, some near-cosmic sea magic entity.” He laughs under his breath. “But when you do wake up… just know that none of this is your fault. We want to protect you, and everything you stand for, Eri. I… might not be able to join your pod, not properly, but I’m gonna be your number one human big bro, got it?” He presses his lips briefly to the crown of her head, between her small horns. “Still family.”

The sound of Hitoshi pulling himself from the water guides Denki’s eyes upward. 

Hitoshi murmurs something in his own tongue, only bits and pieces surviving the echo-like natural translations the Heart offers them: feel, coming. 

Shaking his head, Denki motions him closer until their foreheads touch. “Who?”

Hitoshi’s aurals flick back. Not quite pinned, but flitting nervously. ≈The others from the trench.≈

Oh. Denki’s stomach does a flip, and not in a good way. “When? How far are they?”

≈Not close yet, but making good time.≈ Hitoshi’s lilac gaze flicks to the side, thoughtful but hesitant.  ≈The Heart makes it easier to feel them. Several pods.≈

Even though Denki knows Hitoshi must be carefully controlling what he shares through their mental link, he can feel the siren’s apprehension. “That’s a good thing, right?”

After a few beats, Hitoshi closes his eyes. ≈Don’t know. It means they’re willing to fight to protect Eri. Doesn’t mean they’re going to let her go so easily afterwards. You heard what Mina and Eijirou said.≈

“…That the… the ‘council’? Wants to keep her in the trench.”

Hitoshi’s fins flare in affirmation. His lips part as if he’s about to say something new, when suddenly he goes as still as stone for one heartbeat, two—

—and then tears himself away and spins in place, fins pinned as he lets out a sharp warning hiss.

It’s met with a deep, chugging growl terrifyingly similar to a big cat.

Try as Hitoshi might to position himself in such a way to block the view, Denki sees a clawed charcoal hand slip over and brace on the edge of the stone, and catches a feral red gaze over Hitoshi’s shoulder as Aizawa slides out of the water as gracefully as a prowling panther. 

They’d anticipated that he’d go to the heart, Denki knows. It’s why he’d suggested it. But Nemuri must have failed a second time, and in this very instant, he fully realizes that there’s going to be no reasoning with whatever force has a hold on the man. He can’t move a muscle, locked in place with fear as Aizawa’s features crinkle and his lips pull back over half-sharpened teeth, sights narrowing on Denki’s face like he’s found his next piece of prey to tear apart. It puts to death the notion of this place being safe.

Shit. Shit shit shit.

Hitoshi slides forward a foot and lets out another hiss, and Denki can see the way his mate’s fins flick low, more in fear than aggression. The stress of facing down his pod-sire is undoubtedly counter to his nature and instincts, but not the most alarming problem at hand: the purple mer may have length and his tail to his advantage, but Aizawa seems inexplicably bigger than normal. And, at this moment, he’s got a whole lot less to lose. 

Aizawa lunges—and Hitoshi just barely intercepts, throwing both of them into a roll. 

If there’s any blessing to the situation, it’s that Aizawa seems entirely uninterested (or perhaps incapable) of taking his rage out on Hitoshi as he’d done with Nemuri in the open water. As they tumble across the rock and into the cavern wall, the ex-mer’s gray-black jaws snap close to Hitoshi’s fins and fingers but never on them, and his fingers dig in to the arms holding him back, but never enough to pierce. At every possible opportunity, his attention is drawn back to Denki, eyes like embers and wretched snarl promising a dire fate for the human that dared come to the Heart.

All it takes is one slip.

Aizawa throws himself to one side, then the other—and just like that, he wrenches an arm free from Hitoshi’s grasp.

Denki hears Hitoshi’s sharp “ No! ” —laden with situationally-useless but instinctual Song—only a moment before claws sink into his ankle and drag him roughly away from the chamber wall. 

He chokes on a scream at the burn of it. Tears prick at his eyes and disbelief rattles his heart even as he immediately resists as best he can, slamming the heel of his free foot into Aizawa’s shoulder and face. He knows it’s only Hitoshi’s arm, barred across Aizawa’s neck from behind, that’s keeping those jagged teeth from tearing him apart. 

There’s no reconciling the man who had welcomed him to the family only hours ago with the vicious being currently spilling his blood across the stones of this sacred place. 

Another kick loosens the grip and gives Denki a moment of reprieve. “Mr Aizawa! Don’t do this, it isn’t you, don’t do this,” he pleads, trying to back up. Instead, the charcoal-gray hand finds him again, higher this time, snagging on one leg brace and dragging him even closer. He clenches his jaw through the pain only to find himself left breathless with terror as the man’s teeth snap near his collarbone—scant inches away from Eri.

For some reason, that’s what has Denki move without thinking. He squeezes his eyes shut and lifts his left arm to protect her, shield her. It’s only when those long, predatory teeth sink into the thin but tough material of his dive suit that he figures Eri was likely never under threat to begin with.

He doesn’t hold back his cry this time. He can’t. It hurts like hell, and yet part of him is waiting for the rip and tear that will inevitably be so much worse —

Which doesn’t come. 

Denki dares to open his eyes, and his heart catches in his throat.

Aizawa is still as stone, teeth locked in place around Denki’s arm, but that frenzied, terrifying gaze is no longer pinning him. Even Hitoshi, with his own jaws clamped down at the junction of his guardian’s bare shoulder, slowly loosens his grip and stares, uncomprehendingly, at Eri – who has a tiny palm pressed firmly against Aizawa’s cheek.

She’s awake, Denki thinks, just as the chamber pulses with dizzying, concussive force and a wave of magic renders him blinded and deafened.

It’s almost like one of his experimental flashbangs, leaving his ears ringing and sense of balance utterly fucked, spots of light in his vision that distort everything into high contrast. And as it begins to balance out into recognizable shapes, the first thing he notices is that the dark, looming smear representing Aizawa has become significantly longer.

Denki takes in the sleek black fins, mottled gray scales, and seemingly endless tail draping over the side of the rock and into the water. His attention is drawn back to the man’s—the siren’s —face only when Aizawa’s jaw relaxes and teeth ease away from Denki’s arm. 

Aizawa looks down at his handiwork with twitching aurals and a dazed expression, then across to Eri. Then, with a slurred noise and a double-click, he gradually slumps to the side, unconscious.

The pain in his arm and leg keep Denki grounded, but can’t stop the hysterical half-laugh, half-sob that wrenches itself from his throat. He can see the rise and fall of Aizawa’s chest from here, reassured by it even as a bit of logic at the back of his brain reminds him that if he barely survived what just happened he’d have no fucking chance against a fully formed adult siren. Hell, what would Aizawa be like when he woke up again?

He turns to Hitoshi for answers. “How did— what —”

But it’s immediately obvious that the younger half-siren isn’t listening. His attention belongs entirely to the royal, now sitting up and half-curled across Denki’s abdomen. 

Eri stares back at Hitoshi with candy-red eyes, blinking and transfixed like a toddler. She flicks her fins forward curiously and chirps.

Hitoshi repeats the actions, noises gentle and gaze reverential. Slowly, carefully, he moves closer and bows forward, displaying his decorated thoracic fin just as he’d done for Denki only days prior. This time, however, it feels more like an offering of respect.

Eri wriggles out of Denki’s barely-there grasp with ease, chirping and chirring like a squeaky kitten. She pulls herself over to Hitoshi, not nearly as graceful out of water as the other mer Denki’s seen—these are her first ‘steps’, he supposes—and all but flops down against the siren’s arms and head. Some things must be more instinct than others, as she then reaches up and glides her tiny ivory hand across his offered fin. 

For a heartbeat, Hitoshi is still; then he breaks into the low, pleased trill akin to a purr. When he lifts his head his expression is as soft and relieved as Denki’s ever seen it. 

He can feel his mate’s euphoria from here, even without a full bond. He’s equal parts happy for him and envious.

Then Eri accidentally leans her tail against Denki's injured ankle, and with his own involuntary yelp, he’s brought back to the more pressing reality of the present.

Hitoshi is at his side in an instant, a constant stream of “Sorry, sorry,” slipping from his lips. Rolling up the sleeve of the wetsuit reveals the damage to Denki’s forearm, a series of punctures that hurt more due to the location than due to the severity. The siren moves his mouth to them despite Denki’s initial protest, the cool of his tongue tracing over the punctures and clearing away the blood. Denki flinches each time, but soon the areas are numbed and sealing over just as the cut on his finger did so very long ago. He’d almost forgotten that was a thing.

But when Hitoshi moves to Denki’s ankle, the siren lets out a concerned whine. It’s not hard to see why; the hooking and yanking has shredded part of the wetsuit and left Denki’s ankle a mess. The pain there is sharp and stinging and the claw-marks bleed sluggishly.

Eri, perhaps not understanding, reaches out and touches one of the wounds none too lightly. When Denki yelps, she yanks back her newly red-covered hand and stares at it curiously, chirring in question. It’s halfway to her mouth when Hitoshi stops her with a gentle hand, an uneasy flick of his fins, and a few barely-translated words in Mermish that blessedly have something to do with not being food . The young royal then turns her gaze to Denki’s face, and clicks twice in apology.

“You’re forgiven,” he says weakly, and pushes himself to sit up fully. “Not the closest I’ve come to being food tonight.” 

He glances over at Aizawa, who’s still very much out cold, the fluid, muscular lines of his body intimidating even at rest. The siren’s shirt had been shredded even before entering the Heart, and the sudden change in form and size had rendered the rest of it into little more than torn scraps now abandoned limply over the stone. He’s—he’s so long, bigger even than the red one from the previous morning. If Hitoshi’s nearly a dozen feet from horns to tail-tip, then Aizawa’s gotta be pushing fifteen or more, easily.

Denki swallows. “How did…” he waves a hand at Aizawa, “… that even happen?”

Hitoshi, busy with gently maneuvering Denki’s ankle and peeling away the torn sections of dive suit, murmurs, “Chaos. Ah… Eri has. Her…” he frowns and murmurs the word in Mermish, which the chamber translates.

“Her magic,” Denki repeats. “I—yeah, I guess I should have expected that.” He remembers what he’d learned on his last visit here – how Chaos blurs boundaries, and reshapes—but he hadn’t expected it to be quite so literal. “It’s like she… she rewound him. To what he used to be. That’s crazy.” Then he sucks in a breath and braces himself when Hitoshi moves his mouth to the wounds.

Eri, to her credit, looks pleased with herself. She must understand more of Denki’s words than he anticipated, whether as a boon of the Heart or her own inherent connection to its power. As if to punctuate that thought, she wriggles her way to the wall behind him, stopping only when she’s in front of the golden and purple-black gemstone pair they’d embedded in the wall last trip.

When she draws her fingers over the stones and they light up, Denki flinches and feels Hitoshi do the same. That same presence is back in his mind, like a set of eyes behind his own that’s taking note of every fleeting thought. The mental touch is less uncomprehendingly ancient and more childlike this time, but the undercurrent is identical, both wondrous and wondering. He can feel her studying him. And in turn, he understands the shape of her soul, as vast and powerful as the ocean itself.

If this is what the mer see every time their magic brushes hers, it’s no wonder they regard her with such awe.

Hitoshi hums agreement, or maybe just thinks it. Denki’s not sure. The boundaries between physical and mental blur by the second.

Eri moves on, touching stone after stone, watching as they glow under her careful touches. She pauses at the cloud-shaped one but merely looks at it, ear-fins strangely low. When her palms glide over the three nearby, Aizawa stirs just enough to let out a gravelly chirr and scare the living daylights out of Denki, then mercifully returns to silence. Eri moves on, eventually slipping into the water to touch the others below the surface. Hitoshi watches carefully as if to fetch her if needed. 

This goes on for several minutes. When Denki’s wounds have been temporarily sealed over and his entire foot feels numb, he’s content to watch the little royal and the way Hitoshi trails after her like a doting big brother—or perhaps an aquatic sheepdog.

Then a boom shakes the entire cavern, startling Denki enough that he, too, ends up in the water. Eri skitters behind Hitoshi and they all wait for a new intruder to come down the passage. None do.

There’s something to be said for curiosity, and it’s not always pleasant. Eri finds her bravery and immediately takes off towards the tunnel. Hitoshi, alarmed and caught between chasing her and waiting for Denki, quickly fetches the propeller and hands it over then rushes after his charge. Denki doesn’t wait around; Aizawa will be just fine where he is, he decides, and pulls his dive mask back into place before following quickly behind.

By some stroke of mercy, they’ve paused just outside the tunnel entrance. Denki cuts the propeller at Hitoshi’s side and follows his mate’s gaze upwards. 

It’s too dark to see much, of course, but the occasional flash of light illuminates a sobering sight: the silhouettes of countless divers and a few sinking vessels slowly moving towards the seabed. Several of the bodies, to Denki’s horror, aren’t moving. It chills him to the bone in a way that has nothing to do with the water. The picture etches itself in his memory; he’s sure it’ll be there until the day he dies.

“We should go back down,” Denki says, ice gripping his lungs.

But as his words hit the water, there’s a resounding clack —and Hitoshi is sent sprawling forwards into the dark. Denki swings the lamp on the propeller around to follow him; the light illuminates thick bands of interwoven mesh tangled with the siren on the ocean floor. 

…A net?  

Hitoshi instinctively writhes against it. He’s immediately met with a muted crackling, and before Denki can comprehend what’s happening, the siren’s back arches violently and he shrieks with pain.

His heart lurches, filling with dread. “Hitoshi!”

It’s wired. It’s zapping him.

In other words: someone else is here.

Denki maneuvers the lamp around again, trying to spot their ambusher—and as the rays glint off unfamiliar diving gear he just barely has the foresight to drop the propeller and pull Eri back to his chest, ignoring her surprised squeak. A moment later something broad and heavy impacts his side and snares around the two of them, and Denki forfeits all sense of up and down as the net pinwheels the pair of them through the water like a toy.

He can hear Hitoshi snarling like never before but can’t see him, can barely tell which direction he’s in, as the sound shivers through the deep sea unbounded. Denki fights the urge to struggle—he can handle a bit of shock, it’s practically in his DNA, but he won’t risk Eri having to do the same. Instead he reaches for the emergency switch of his suit’s communication system. Yamada might not be able to help, but at least he’ll know they’re in trouble.

Then there’s hands on the net from the outside—grabbing for Eri’s tail. She hisses with all the fury of a frightened kitten and shies away as much as the ropes will allow, burying into the safety of Denki’s side. 

“Get off of her!” he snaps, shoving at the hand and bundling her close. Maybe they can’t hear him, or maybe they just don’t care, as the hand comes back as a fist and slams into the side of his mask—nearly knocking it loose. So instead he curls into a ball, tucking his face between the small pearly horns at the top of her head. He can’t let them take her. He won’t.

Hitoshi calls his name. 

He’s further away now, Denki can tell; they’re being dragged apart. He thinks he can feel Hitoshi’s terror and rage echoing his own, and jolts when the Song slips through the water like silk put to sound. 

Release – release us – drown – dr—

It cuts off with an audible zap and another sharp, jagged shriek of pain.

Fear curls ugly and dark in Denki’s gut and it’s all he can do to lock it down before it becomes full-blown panic. 

“Hitoshi, stop, ” he cries back, hoping his siren can still hear him. He’s rewarded with the faint sensation of an unspoken question at the back of his mind, tight and worried. “Don’t give them any reason to hurt you!” 

It’s a stupid thing to say, he knows that as soon as it’s left his mouth. He can’t ask Hitoshi not to defend himself. For fucks’ sake, they tried to harpoon him earlier. There’s no guarantee they’ll keep him unharmed even if he does cooperate, and for all it’s worth, playing nice just isn’t in Hitoshi’s blood.

He’s yanked further upwards. “I’m sorry. I’m sorry! I’ll—I’ll protect her!”

The words are met with silence and darkness.

The ascent is slower than the descent by virtue of safety measures. Even if the divers holding his net don’t care for Denki’s wellbeing, they’re not apparently not willing to jeopardize their own by surfacing too fast. Focusing on releasing air gradually from his buoyancy compensation device offers the dual benefit of giving him a distraction from his fear and preventing a horrific accident. He can’t see or reach his gauges from how he’s tangled up, so it’s a bit of a guessing game, but better than not trying at all.

Eri, for her part, is curiously quiet. If it wasn’t for the way she shifted now and then to peek out of the net at the ever-lightening waters, Denki would have believed her to be sleeping again. He can’t afford her much free space as it is, and near-constantly apologizes for it as they’re dragged higher and higher towards the surface. He dearly hopes he can keep his word. 

This might be the only time he gets to prepare for what’s ahead, he realizes in a moment of clarity. His best chance at putting up a fight. He feels his makeshift taser in the pocket on the inside of his vest, and says a quiet thanks to whatever gods are listening that they hadn’t gotten zapped like Hitoshi. He quickly maneuvers it into one sleeve, and bundles the unfinished explosive—thoroughly a dud—into the other.

And then, at long last, they breach.

The dragging doesn’t stop there. He’s roughly manhandled aboard a boat, knees in agony as they knock against the deck. He chokes on a sob and curls over at the throbbing ache of it, ghosting his hands over the joints. 

Eri gently touches his legs with a quiet, confused chirp, worry in the pinning of her fins.

“It’s—it’s okay,” Denki says through gritted teeth, trying his hardest to summon a smile. “They’ll be okay. Just—hurts. Y’know?”

He doesn’t know if she understands. He hopes she does. But what matters at the moment are the approaching footsteps that pause directly behind him, and then the boot that digs a heel into his shoulder to roll him onto his back.

A disbelieving huff. “You again?”

Denki wriggles out from under the boot and promptly shoves off his diving mask, blinking up at the figure looming over him. Ah. It’s Okuta—or Giran, as his companions called him. Denki subtly pushes his arm against the deck until the taser slides out of his sleeve and into his palm.

The man chews on the end of a cigarette and glares down at him. “Tell me, kid. Why is it we keep finding a random crippled mechanic entangled with the last merfolk on the planet?”

Denki manages a jaw-clenching grin. “J-just luck, I guess.” 

Giran pauses at that, then wheezes out a laugh. “Got a sense of humor even when you’re eating shit. I can respect that. But lucky for who, exactly?” He turns to his lackeys. “Separate ‘em.”

Fuck that, Denki thinks, and the first one that reaches for Eri gets the prongs of the taser directly to her bare inner arm. As that one seizes and reels back, a second gets close enough to yank the young mer’s tail. Eri slides a few inches down Denki’s chest with a yelp; it echoes through the night air just moments before her attacker gets Denki’s good foot to the side of his knee.

Before the third can close the distance, Denki kicks up against a partition and brandishes the explosive.

“Touch her again and I’ll put this whole boat underwater,” he challenges shakily, pulse thundering in his ears. 

Giran sneers at him, but seems to think it over for a few seconds. “That’d be suicide. You can’t swim, brat. Look at you. You’d fuckin’ drown.”

“Sure,” Denki says, swallowing tightly. “But she’ll get away and be protected in a heartbeat. And that’s good enough for me.”

“Is that so.” The man pauses. “Can’t say I believe you. Y’see, last I heard, your purple fucker was getting all wrapped up nice an’ pretty for the highest bidder. Unless you think it’ll be able to help from a private aquarium? If someone buys both, maybe. Ain’t likely, mind you, given the price tag they’ll fetch.”

A wave of revulsion kicks Denki in the gut. He fights to keep his voice steady. “W-well. It’s not him you need to worry about.”

Giran chews the end of his cig, gaze flicking down to Eri then back up. “You’re bluffing.”

Denki smiles again. “Am I? Is that a chance you really wanna take?” He forces a laugh and displays the arm with the ragged bite marks. “There’s a bigger fish than ‘my purple fucker’ down there now. And if he’s willing to eat me to keep her safe, what d’you imagine he’ll do to you?”

A beat passes, and another, and it seems even this crafty poacher is reconsidering. Denki holds his breath and waits for a verdict, faulty bomb held aloft like a nuclear detonator.  

The deciding voice does not come from Giran.

It comes as a rumbling croon, long and drawn-out, a searching noise from across the water. A tone Denki’s never heard Hitoshi make, he’s certain, but this isn’t Hitoshi. It’s too high-pitched and fluttery, like a Song without singing, a vocal melody simultaneously foreign and familiar. 

Eri looks up, her aurals spreading curiously as she stares out into the waves. 

The sound pauses pauses, then begins again. Another voice joins it. Then another.

And, before Denki quite makes sense of what he’s hearing, Eri scrambles upright and answers with what he can only describe as a yip.

He very nearly lurches with realization. The trench mer made it. They made it, and they’re looking for her.

“Fucking kidding me,” Giran snarls, seemingly reaching the same conclusion, the paling of his face visible even by the boat’s dim lighting. He steps back from the rails and adjusts the devices at his ears. He’s clearly weighing his options, jaw tense and gaze calculating as it snaps from Denki, to Eri, to the navigation pad of the boat. 

Then, with a huff, he stalks out of sight. “I’m calling the kid’s bluff. Toss ‘em both in the livewell,” he calls. “I’ll take care of any ‘bigger fish’. And all the rest.”

Denki very nearly loses his grip on the explosive as his net is dragged backwards. Still, he sees one of the other lackeys hesitate.

“Giran,” the man says. “The sonar? But the other divers—”

“Tell ‘em they have five minutes.”

What?

No. No no no.

The voices of the mer continue on beyond the boat, beautiful and entrancing and hopeful, but suddenly their presence fills Denki with dread. 

“You—you can’t do that!” he shouts after Giran, reaching through the gap in the net and snagging a bar to prevent being dragged. “You’ll kill them!”

The man who’d initially protested gives him a long look, then shakes his head—and stomps on Denki’s hand and walks away to the sound of his cry of pain.

And the next thing Denki knows, he’s falling. 

The livewell isn’t terribly deep, but it is devoid of water. His back hits the bottom hard, quickly followed by his head and legs, and the pain is immeasurable as he feels something in his lower half fracture as Eri lands just the wrong way. He knows he’s screaming but it’s beyond his own hearing, outside of him, somewhere else. 

They don’t bother to put the lid back on the well. There’s no point.

It takes half a minute for Denki to get his breathing under control, to separate the situation at hand from the memory in his mind. It’s not an easy task. His gasps echo just the same, the darkness creeps in just the same. But instead of rock and rubble on his legs, it’s a young mer, and he’s got nothing, nothing left to trade for hope.

Eri rolls off of him, and the jostle of it has Denki strangling down a yell. She offers a whine in turn, and though he can’t see her face, he feels the weight of her gaze on him.

“I’m sorry,” Denki hiccups, reaching blindly for her. Her finds her arm, and traces it down to her small, webbed hand. “I’m sorry, Eri. I’m sorry. I tried.”  

There’s no chance of keeping it together. He’s at breaking point. He can’t protect her, he can’t protect anyone , and he’ll never get to apologize to Hitoshi for it. 

Eri chirrs. 

Denki can feel her moving closer in the darkness, the pressure of her other hand on his sternum as she leans her weight on his chest. It hurts, but it’s nothing in comparison to the rest. And, when her hair brushes the sides of his face and he realizes where this is going only moments before her forehead tentatively touches his, he barely withholds his flinch of surprise.

It’s nothing like sharing a headspace with Hitoshi. 

Eri’s presence is immutable, unavoidable, everywhere . Strange but not invasive, she feels like a lullaby or a gentle smile or a deep breath, something natural and beloved. Denki tries to understand her feelings and the reason behind the action, as he’d done with Hitoshi, but when he reaches out for them, he finds only vastness. A sky full of clouds. A sea full of song. 

A familiar, ancient touch.

Just the same, he thinks. 

Denki swallows, closing his eyes. It’s been on his mind since his first visit to the Heart, when he’d touched Chaos and felt its eyes in the barest parts of his soul. “It was you, back then, wasn’t it? Some version of you that took my deal.”

The confirmation feels like warm waters, a gentle hum, a playful chirr. Eri’s fingers curl against his chest.

“Yeah,” Denki murmurs, “I think… I’ve known for a while.” He shudders a ragged sigh, pinching his brows together as if it’ll stop the burning in his eyes. 

It doesn’t. He can’t feel anything except guilt and agony, breathing in hope and exhaling it as broken promises. In his arms, he holds an entity as old as magic itself; a gods-given wonder, practically a deity in her own right. A spirit of the sea and storms and song. And as soon as the rasyakiin recognize her for what she is…

A terrible grief steals over him, and he shakily raises his hands, cradling her small head with his palms.

They’re running out of time, the voice at the back of his mind reminds him. The sonar ping will rip through the water any minute now, the battle will be lost, and so will any dream of the colony’s future. As tears track down his face, he tries to share this notion with her through their linked consciousness, to break through the veil of innocence and wonder so she understands the monstrousness of his own kind.

“Please, Eri,” he says, voice barely even a whisper. “I d-don’t know what I have left to give, but you can have it. Any of it. J-just keep yourself and Hitoshi safe, however you can. P-please. ”

His blood. His heart. His soul. His life.

He’d give it all.

“Please.” It’s little more than a breath.

He feels Eri’s hand open and flatten on his chest. Light blossoms somewhere just beyond his eyelids. Denki readies himself for oblivion, letting fear mellow into relief, and prays that it’ll be enough.

Cold seeps from her palm into his lungs, up his throat, down his spine. It feels like a breath of fresh air and neutralizes his pain as it reaches through every inch of his being. In the deepest recesses of his awareness, he hears tides upon the shore, their gentle push and pull surrounding him. And just as he feels like he’s slipping from his humanity and becoming one with the waters for good, three whispery words take shape at the forefront of his existence:  

become  
             whole
                       again.

Denki tastes the stars. 

Energy tears through him like a riptide and drags him violently back into reality. It buries itself in his chest, a pulsing and burning source of power that he’d long since forgotten the shape and feel of. Affinity. It’s enough to have him buckle upright and wheeze, tears tracking down his face unhindered as the old paths of magic light up like highways through his body.

The glow of Eri’s horns flicker and fade. She slumps against him, awake but dazed, offering a weak trill as Denki lifts her head.

Their eyes meet just as lightning flashes overhead. The burst of thunder is nearly simultaneous and shakes the air in every direction. 

Eri smiles.

He understands. Gods, does he understand. He could cry for it, cry for the fact that for the first time in years, he's numb to the pain as he gathers his one unbroken leg beneath him and rises to a half-kneel. But there’s no time for gratitude.

Denki lifts his gaze to the clouds and feels the power there offering itself. 

For the first time in years, his affinity answers. It smells the ozone. It’s hungry.

With a crackle like laughter, the storm offers a brilliant hand of lightning—and Denki reaches up his own to meet it.

Chapter Text

For an indeterminable amount of time, all Denki knows are light and heat. The storm’s power is immense. It’s inside him and out, pure white-hot energy that prickles and crackles along his too-human skin and asks with growing impatience to be more. He’s lightning incarnate. An avatar of the storm. His eyes burn; his teeth ache. He can’t tell for the life of him if his heart’s even still beating.

The lightning in his veins is just this side of painful, but he’s conscious of it, which means he can’t be dead just yet. It’s a testament to his affinity that he’s still alive, he’s sure. But as the borrowed power finishes chasing down his arm and into his ribcage, ricocheting sharp and dangerous around his core, he knows he must use it now or risk being burned up for good.

He pushes himself to stand. His broken leg is numb to feeling, but it still can’t take his weight. That’s fine, he thinks. Even just being upright should have his head and shoulders above the rim of the livewell and give him a clear view of most of the deck.

The lightning striking the middle of the trawler didn’t go unnoticed, of course. So, when Denki pops up like some unkillable weasel, hair wild with static and almost vibrating from the amount of energy under his skin, it stops several of Giran’s rapidly approaching lackeys in their tracks.

He grins at them. “Peekaboo.”

The first to recover from the surprise reaches for him, and before Denki can warn her off, her fingers brush his shoulder. With an audible electric pop, she immediately jolts in place, eyes going wide and rolling back as the currents throw her muscles into abrupt seizure.

Denki shoves her off and lets her fall to the deck. It’s so unbelievably satisfying to see the spooked expressions of the others; he could get used to the upsides of being a human taser. The involuntary static discharge had relieved him of some of the overloaded sensation setting his affinity alight, but he’s still got plenty of reserves to spare. He’s not out of the fight now, not by a long shot, and the storm continues to laugh overhead.

It’s time to act.

The familiar shape of his affinity stretches out before him in his mind, sated and awake and ready. It’s just as much an old friend as it is an instinctive part of him, and when he asks it to release the lightning, it’s more than happy to do him the favor.

He raises finger-guns in the direction of the nearest pair and lets his magic loose. Thunderbolts chase down the path of his pointing and lurch eagerly at the target like hounds on a hunt, filling the air with frenzied crackling and the sharp scent of ozone. He doesn’t wait after each one that falls, can’t allow himself to worry about what kind of state they’re in as they hit the ground and jerk. As Denki stares down the line of his arm to the one that had stomped on his hand, now stumbling backwards, he swallows. You made your choice, he thinks. I can’t let you kill them all.

The man goes down just as easy as the rest.

Then the deck is quiet. Logically, Denki knows it’s not over yet. He hasn’t seen Giran, which means the controls for the sonar must be further in. He braces his arms on the edge on the livewell and heaves himself up and over, toppling ungracefully onto the worn planks on the other side. It should be alarming that he can’t feel anything when his damaged leg smacks down—certainly isn’t gonna make recovery any easier—but there are bigger issues brewing, so for now he counts it as a blessing and reaches back in for Eri.

It would be faster to leave her to hide and wait for him, but after everything, the thought barely forms in his mind before he dismisses it. He’s not letting her out of his sight. He quickly fetches the discarded sling and wrangles her onto his back. Her childlike arms wrap around his neck; he can feel her head lolling against the base of his skull, her small horns prodding him when he adjusts her weight higher. No wonder she’s tired, after the kind of magic she’s already let loose today.

“Hang in there, yeah?” he murmurs as he grabs a nearby skimmer pole to use as a makeshift cane. “We’re gonna take him down. We’re gonna save them, and then Hitoshi. It’s—it’s gonna be fine.”

In the dark around him, the calls of the mer begin again. A few are the beautiful, bell-like chimes of what instinct tells him are the coral-fins, more melodic and whimsical even in the midst of the storm. Others remind him of Hitoshi’s lower trills, and make the hair on the back of his neck stand on end. Sirens, he’s sure of it. They’re both here, and he can only hope that they’re all friendly.

Eri offers a reassuring chirp, and that’s probably all that’s keeping him from ending up in the water with another set of teeth buried in his skin or the chant of drown overriding his survival instincts.

He can feel their eyes on him. Beyond the railings of the trawler, where the dark waves slap up against the side of it, he senses their presence. He dares not seek out their gazes with his own. And so, with one unsteady step after another, he instead sets his sights on the deckhouse.

The distance can’t be more than two dozen feet, but every goddamn inch is a test of Denki’s balance and determination. Even from afar he can hear the navigation systems blaring, the proximity radar doubtlessly screeching its alarm at all of the unexpected visitors surrounding the small vessel in the dead of the night.

When he reaches the door, he’s expecting Giran to come out swinging fists or magic or both—but instead the man’s leaning over the console, head hung low. One hand is splayed across the base of the radar screen, which is alight with so many blips that it’s hard to differentiate one from the next. The other hand has three fingers gently tracing the outline of a rectangular red button marked with radio waves and the kanji for caution. The safety cap for it is raised; he’s been waiting, clearly.

Denki holds his breath in terror until it’s clear that Giran’s waiting for something. Him, maybe.

“You don’t have to do this,” Denki says at last.

Giran doesn’t flinch, doesn’t show any surprise. He just hums acknowledgment and shifts his weight to pensively stub the toe of one boot against the floor.

“I mean it. The mer, they’re forgiving, if you stop now then maybe—”

“What do you know, kid?” Giran spits, interrupting him.

Denki only falters for a moment before answering, “I’ve tried to take their magic before too.”

Finally, Giran tilts his head to peer at Denki from under the arch of his shoulder and arm. His glare narrows. “Hn. Figures. People don’t generally end up rubbin’ shoulders with mythical folk without hunting something that belongs to them.” He kicks up from the console, turning and staring down the length of his broken nose. “You made a mess of my crew, you know that?”

When Giran reaches for the breast pocket of his vest, Denki raises his finger-guns and lets sparks hop around his hand and arm in warning. He’s not going to fall for the cigarette trick a second time. Fool me twice, and all that.

The man’s hand slowly drops to his hip. “And here I took you for a pushover,” he mutters. His pink stare flicks over Denki’s shoulder to Eri, then back. “Alright. What’s it gonna be? Have you got some heroic speech all ready for me? Gonna try and offer a truce on behalf of all the creatures just waiting out there to tear me to pieces? You may have magic now, boy, but don’t think they’ll let you speak for them.”

Denki focuses on one part of the response and lets the rest drift by. “Do you want a truce?”  

Giran is quiet for a moment, chewing on the inside of his lip. “It’s true what I said before, y’know. Even if your finned friends manage to hold us off, that won’t be the end of it. If not us, it’ll be others. I’m just the broker, if you catch my drift. The guys in charge’ll—”

“Do you want a truce?” Denki repeats more forcefully.

For a moment, he can see a spark of something like regret in the man’s eyes.

“Sure, kid,” Giran says with a crooked, pained grin. He swiftly fetches a cigarette before Denki can so much as protest. “But I’m ‘fraid it just ain’t in my cards.”

He reaches for the sonar button.

Perhaps it’s because he’d already been raising his hands that Denki just happens to be faster.

He doesn’t think to hold back. Every fiber of his adrenaline-saturated being fixates on the sole idea of stop Giran, and even as he shouts the words they’re drowned out by a deafening snap as the magic within him obeys.

The room sears white in an instant as his electricity lashes out in one jagged, vicious bolt as broad as Denki himself. He can’t see Giran for the flash of it, but can hear metal rending and machines shorting, and he’s pretty sure the whole damn ceiling tears open as the storm sees the action and decides it wants to play.

It’s too much. Too much. He smells smoke and tastes ozone so sharp that it’s nearly acidic on his tongue. Just like on the initial strike, Denki’s thoughts buzz and scatter like the many fingers of lightning that reach for every corner of the deckhouse. The whole boat crackles with it; moments later, metallic shrieks answer him as the sonar panel—and likely several other crucial instruments—explode and knock him off his feet.

In one instant he’s supercharged, and in the next he’s nothing at all.

Denki doesn’t remember much immediately after that.

When the world does come back, there are hands on him. Bad ones, or maybe good, but he’s in the water at some point and isn’t drowning, so he’s inclined to say the latter. His gaze blurs and dims and he can’t seem to quite organize his thoughts beyond the simple concept of being pleased with himself. He did something right, he’s pretty sure, though that’s about as far as his reasoning seems to take him.

Someone says his name. They’re saying things. A lot of things. He tries to focus on them, but his eyes have other ideas. So he just smiles and hums.

They push back his sopping hair and laugh. They might be crying, too.

He comes back to himself gradually at first, gaze finally focusing in turn on the brown-haired girl leaning over him. Then, without warning, everything slides back into place all at once.

He sits up fast, nearly head-butting Uraraka, who yelps and dodges just in time. The floor below him lurches, his fingers skidding against polyethylene instead of planks. A quick scan of his surroundings tells him he’s on a small, unfamiliar boat instead of the Midnight Lady.

“Kaminari?” Uraraka says hopefully, brushing at her cheeks with the heel of a palm. “Can you understand me now?” 

Denki genuinely attempts to say ‘yeah’, but opens his lips a bit late and the result is more of a “Mmmeh!” He sucks his teeth with a frown and nods instead.

Though Uraraka opens her mouth, surely to voice more concern, it’s a different voice that comes next.

“You fucking idiot,” Bakugou says, shoving him prone again with a hand on his shoulder. Hadn’t seen him back there, oops. The other blonde’s face is marked with soot and sweat and his gaze is more than a little battle-wild. “What the hell was that, creaky? D’you know how lucky you were that the fish’s friends were nearby when you went under? What was it that you fuckin’ set off that tore a goddamn trawler in half?” 

“Hm?” Denki blinks, and clumsily raises his hands into his range of vision. “Mm... me?”

With barely a conscious thought, he twitches his fingers purposefully, and watches the threads of lightning dance between them.

“Me,” he confirms, grinning.

Uraraka gasps; Bakugou sits back on his heels and pulls a hand away as if he doesn’t trust Denki’s captive sparks not to bite. “Thought your affinity was busted,” he murmurs suspiciously.

Denki nods. He tries to convince his numb lips to form the shape of an ‘E’, eager to explain what happened, when he realizes that the very important, very vulnerable mythical being responsible for restoring his magic to him is no longer attached to his side. He sits up again quickly, shoving away Bakugou’s attempts to push him right back down, and tosses his gaze around in a panic.

“—Rrrri. Errrri?” His tongue is like lead between his teeth.

 A small, pleased chirp sounds from behind him and he turns in place just to confirm it with his own eyes.  He’s so relieved; she doesn’t look worse for the wear at all. She’s curled comfortably at the peak of the bow like an aboveboard figurehead, scant feet away, blinking back at him curiously.

“Whuh—where?” Gods, this is getting annoying. He scowls and rubs at his face; it feels like pins and needles as normal sensation slowly returns. “Hitoshi? N‘muri? Wher’re they?” And after a moment, adds, “Wher’re—where are we?”

The two of them share a rapid look.

“The witch is back on the Lady,” Bakugou mutters. “Cheeks bandaged her up before we went looking for you—but then some fucker took our sea-doo down. So I stole his boat.” His smug grin is short lived. “Heard what happened to Aizawa. Can’t fuckin’ believe it; the asshole’s always been so steady. Good that you stayed clear, I guess.”

Denki laughs weakly, working his jaw. “Mm… well. About that.” He looks down, knowing their gazes will follow, and rolls his forearm to reveal the rips in the sleeve of is wetsuit. The reddened arc of tooth marks and bruises, some already scabbing over, is visible beneath the tearing. “We uh, didn’t.”

Uraraka immediately pulls out her small medical tote again. “And here I thought it was Bakugou’s recklessness I was preparing for!” she says with a strained huff. “Sorry, Kaminari, I got so focused on your legs, I didn’t notice—”

“He’s dangerous?” the red-eyed blonde cuts in, deadly serious. 

Denki shakes his head, then thinks better of it and shrugs noncommittally. “He… was. Maybe still is… not sure. But I think—I think he might be back to himself now. Sorta.” He swallows. It takes effort. “We left him in the heart after Eri turned him back into a full siren and he passed out. Seemed lucid for a moment, y’know? Hitoshi stopped him from—wait.” Dread crawls up his back. “Where’s… you haven’t seen Hitoshi?”

“We thought he was with you,” Uraraka says gently.

Denki rolls to his front—shit, he’s starting to feel pain again—and looks out at the boats. There’s far less of them than there were earlier in the night.

“We—we got netted. Separated.” Worry blooms thick and heavy in his chest, moving for his throat, squeezing it. He’d done his job, he’d protected Eri, but now… he nearly chokes on his next breath as he remembers Giran’s threat. “They’re going to sell him.”

Some of the boats must have fled. What if Hitoshi is on one of those? What if he’s already gone?

Eri would know, he reasons through the panic. They have a pod bond. He turns to the small royal and crawls forward, ignoring his pain and Uraraka’s protest as he yanks away from her care.

But when he reaches her, he’s treated to a clear view of the water below—and the dozens upon dozens of mer gathered there, staring up at him as a collective. He stills, shocked.

“They brought you up,” Ura explains in a quiet voice, “and haven’t left since.”

Their gazes are unsettling. Now that he’s meeting their eyes properly for the first time, it’s enough to make him freeze, like some terrible spotlight has been turned his way. Hitoshi had claimed there were what, thirty at most? But there are so many, and so varied, that they’re almost impossible to comprehend. Here, a pale blue male with a plain face and a fin like a mohawk. There, another in mottled browns and white, her horns long and rounded like a rabbit’s ears. The biggest and most prominent, a broad navy-and-red siren marked with rippling stripes like flames, face set in a deep scowl. 

Something about the last one strikes him as maybe being a leader, but while Denki’s trying to scour his brain for those greetings Hitoshi taught him, a croon echoes from beyond—and the masses shift without a word.

It’s no wonder. The mer that approaches as they part is perhaps the largest single being he’s ever seen up close.

He’s golden all over, save for brilliant blue eyes set deep in sunken sockets and a touch of the same color at the edges of his fins. The length from his hair to his waist alone must be five feet, maybe six with his fiercely impressive horns; the thick, trunk-like mass of his tail goes on and on into the oblivion below. But, for all that he’s gargantuan and likely able to hold Denki around the middle with the breadth of one spindly hand, the expression he wears is… gentle. Kind. And strangely human compared to the rest.

The mer stops a few feet away. The spotted skin around his eyes crinkles as he smiles and lifts his golden head from the water.

Then, “Hello, young one,” he says in slightly clumsy but perfectly understandable Japanese.

Denki nearly falls off the side in shock.

Bakugo and Uraraka scramble up beside him. The former swears under his breath, surprise or awe, he’s not sure. Denki doesn’t blame him. He’s still trying to backtrack in his brain and now figure out an appropriate greeting in his own language.

The golden mer laughs. It doesn’t sound natural—it never is for merfolk, Denki knows, so it must be a learned behaviour—but the fact that he does it at all feels like an olive branch of sorts. It erases some of the fear that comes with staring down a fleet of mythical creatures, every one of them peering up curiously from the water.

Denki swallows. “Hi, uh.” What was that word for respect Hitoshi used? ≈Sosvii.≈

Several of the mer below twitch their aurals in surprise and renewed interest. Denki takes it to mean that his too-breathy Mermish isn’t insultingly awful, at any rate.

“How d’you know Japanese?” Bakugou asks suspiciously before Uraraka can elbow him in the gut with a hiss of ‘be polite!’

Another smile. “There was a time when our people interacted more freely, my boy. The colony welcomed walkers and swam with them as chirruk. Friends.” He tilts his head and spread his long, intricate aurals, calm and open. “Long past, but some of us would see it happen again.” His sunken eyes flit to Denki. “You fight for us, do you not, little one?”

Denki cut in. “Y-yeah, for—for Eri. And for—” His stomach drops to the vicinity of his knees. Guilt hits fast and makes him want to hurl. “Hitoshi, oh shit, I—I got distracted—I still don’t know where he is! Please, Hitoshi—”

There are a few hisses and other abrupt sounds of discontent below at the name. Wide-eyed, Denki’s gaze hops from one face to the next—irritation here, uncertainty there—and he abruptly remembers that this colony had kicked Hitoshi out, and all because he’d felt the ley-line waking. It’s enough to fill him with cold.

“If it wasn’t for him, and all that’s happened, Eri would be in their hands already,” he says shakily, reaching for the small royal. She comes to him easily, curling into his side. “They—they share a pod, you know. He bonded with her before anyone else.” His throat feels tight. “And. He’s my mate.”

It’s the first time he’s said it out loud, he realizes as the word passes his trembling lip, final and acknowledged. The majority of them probably don’t understand him anyways, but it makes it more real all the same. He sees the apology in the golden one’s gaze. He wishes desperately, with his whole being, that Hitoshi was here. Instead, his mate is tangled in a net somewhere on a boat, fear spiking as he realizes his own fate.

The thought has Denki pause, holding his breath.

He’s been so distracted by his own issues at hand that he’s forgotten. For a moment, he withdraws into himself just to be sure; there are two strains of fear running parallel in his brain, one close and personal, the other faint.

Uraraka touches his shoulder, murmuring something.

He tunes her out, raising a hand. “Wait—h-hold on, just…”

Denki closes his eyes and forces himself to relax, pushing away his own chaotic brew of emotions and reaching for the peace of the Heart below. It’s easy with Eri’s small hand light upon his wrist. Calm rolls in, then he lets the poisons of panic and anger wash out with the tide. One breath, two. After mere seconds, his mind is deep under the sea, and behind his eyelids he sees the yellow and purple stones pressed tightly together in the chamber wall. 

They might not have a mate bond, but they are attuned—through the Heart. Through Eri.

He mentally brushes the purple stone, turning to that sixth sense at the back of his mind.

Eri chirps in understanding—

And just like that, Denki can feel him.

It’s all Hitoshi’s fear now. Hesitant and sparking, as if he’s refusing to acknowledge it, refusing to give into the idea that fate has decided this for him. It twists and intertwines with cool resolve and burning rebellion that are so definingly Hitoshi it hurts, fierce emotions that Denki’s never clearly recognized in the siren before, but now that he’s touching them, they may as well be branded into his mate’s DNA.

Where are you? he thinks, and there’s a flicker in the intensity on the connection’s other side. The faintest ripple of surprise, a few drops of confusion. And then hope, making Denki shove as much encouragement as he can through their unsteady link in a constant stream of it’s me, it’s me.

But just sharing their quiet reassurances isn’t actually helping bring them closer outside of the mental space, and it’s with a gut-wrenching hold on that he pulls back from the connection to surface in his own five senses once more. He’s not surprised to find the wetness on his cheeks, but the sound of Bakugou chewing out the golden mer for not jumping into action sooner is a bit more jarring.

“He’s still alive,” Denki says, voice rough as he rubs at his face with a hand. Everyone falls silent, attention on him again. He sniffs and looks down at Eri.

She meets his unspoken question with a knowing look, then spreads her fins.

It gives him the confidence to turn back to the mer. “Translate for me?” he says to the golden one, who flares and nods simultaneously in reply.

This time, he can’t be intimidated by their piercing and searching gazes. He tries to meet each and everyone one before speaking, pleasantly surprised when he spots Hitoshi’s two friends and they blink cheerfully back at him.

He takes a deep breath.

“So—I know that a lot of you only came up here for Eri’s sake. I get that, she’s… she’s special, crazy powerful and important, and now she has a bigger target on her back than I’m sure I can even comprehend at this point,” he rambles. “Or maybe you’re here because of an old debt. Which is fine.”

He waits for the translation to catch up, and watches the different reactions. From the ones he visually pins as coral-fins and potential hybrids, he’s met with proudly broad aurals and a few confident chirrs. Some of the sirens look torn, and a few even narrow their eyes. That’s fine. If the unfriendly ones want to return to their trenches after all this is done, he’s not gonna try and stop them.

Denki swallows. “But the colony grounds? They’re not a lost cause. I’ve seen the ruins, and I’ve been to the Heart. We’re floating over a legacy right now that doesn’t have to be left to human history books and fairy tales. And despite what you’re seeing here today, the world on the surface has changed in the last century. These guys? They’re the exception, not the rule; there’re laws, and treaties, and—and so many people like us.” He taps his chest. “Who wanna see you all thrive.” Then he looks at Eri. “This is where your royal belongs, and I know you know that, yeah?”

This time, there are more signs of agreement, if hesitant ones. It’s only when Eri flares again herself that several others that held off resignedly join in, looking at her as if they’d give anything to keep her happy. They probably would. It’s built into their very existence, after all.

“And if there’s anyone you all owe for her safety and the future of this colony that she’ll lead, it’s Hitoshi. He—he gave up everything for this.” Denki forces his voice not to waver even as he dips himself into a fully prostrated bow, head pressed firmly against the deck. “Please don’t let them take him away.”

He’s met with silence.

Then the giant in front of him murmurs, “Zyaroshii, we are honored to help.”

Part of him wants to ask the meaning of that word—it’s said like a title, respectful and kind, and makes his chest do a little swoop even without knowing what it stands for. But every second wasted is another second that Hitoshi’s being pulled away from him, so instead Denki struggles back to his feet and nods his thanks, feeling the hum grow beneath his feet as Bakugou readies the motor.

The great golden coral mer laughs again. “Take a seat, young ones,” he says, then chirrs out across the water.

Immediately, like a chorus, dozens of others answer—and the flood of magic that surges from the sea is suddenly thick enough in the air that it feels like a solid weight pressing in on Denki from all sides, initially terrifying but then evening out like a blanket—and the sea moves.

He collapses into a seat just as the boat drags forward, and judging by Bakugou’s yelp, it wasn’t his doing.

Despite the way that night clings to the world like it’s afraid to let go, it’s as if the sun has risen below the water, fractured by the waves into shards of brilliant color that paint the sea like living stained glass. But it’s not just color, Denki realizes as he dares to lean and stare into the water that’s carrying them along—it’s the mer themselves, lifting and lowering themselves just beneath surface, gliding along near-effortlessly despite the unreal speed he knows they’re moving at. Each one glows with their own unique hue of magic, contributing to the otherworldly waves of rainbow-and-gold light that is urging the collective on towards the horizon.

Towards Hitoshi.

The thought snaps Denki’s gaze forward again. Eyelids fluttering down, he focuses on that connection again, thankful that Eri seems to have kept the connection open to guide the colony onwards through a series of soft trills.

Hitoshi’s presence is more alert now, actively searching when Denki reaches out to him and eager to meet him halfway. It’s a bond without sound, without sight, but it’s enough that Denki can tell with full clarity that his mate hasn’t given up. Won’t give up, judging by the fierceness with which Hitoshi shoves a steady blend of hope and reassurance through. Denki’s not oblivious to the pain that lurks underneath, but the siren clearly isn’t too occupied with it, which eases his worry a tad.

We’re coming, he thinks, and is met with a deep, desperate warmth in return.

It’s hard to judge the passing of time with half his thoughts outside of himself and the other half spent keeping himself upright in the seat. At one point he hears Uraraka saying something about the Midnight Lady following behind them, and about the lights of the Shinkai Maru in the distance—but it’s only when Bakugou unsteadily finds his footing and mutters, There, that must be it, under his breath that Denki is pulled back to attention.

The boat ahead is difficult to make out at first, until the light of the colony begins to catch on painted stripes, iron attachments, and the rolling tides of its wake.

It’s fast, but they’re faster.

A section of the mer below split off, advancing like a battalion towards the target while the remainder pull their own little stolen craft up alongside to keep an even speed. It’s only when the other boat is backlit by magic that Denki sees him, a silhouette strung up on ropes like a caught shark, thrashing against his restraints as the poachers on board scramble to make sense of their impending fate.

Hitoshi’s wordless snarl echoes across the water, and Denki, throat tight but shoulders set determinedly, shouts, “I’m here!”

He can see the chaos unfolding onboard; at handful among the poachers’ number are screaming cut him down and let him go, dropping their weapons and moving away from the edges of the vessel. Many others lean over the railings, guns and crossbows pointed at the beings beneath—some missing, some hitting, some misjudging the distance to the waves and finding themselves at the mercy of the mer who surge upwards against the ship and drag their victims back down with them.

Denki can’t find it in himself to feel sorry for those ones.

Despite the way that the poacher’s vessel fights to charge on ahead, it seems to be slowing, dragged back by the magic-laden waters it’s trying to churn. This serves only to further divide those upon its deck as they realize the futility of fighting the sea when there’d no land to be seen in any direction.

They pull up alongside. Denki takes a deep breath to call out, but finds himself staring up the barrel of a rifle, blood freezing in his veins as he meets the terrified gaze of the man on the other end.

“You call them off,” the poacher barks at him, voice unsteady. “You call them off before they kill us all!”

You started it, Denki wants to point out, but keeps that to himself. Instead, he slowly raises his arms, feeling the crackle of static along the back of his hands—a precaution.

“Not until you let him go,” Denki replies as steadily as he can, nodding towards where Hitoshi hangs tangled in rope and nets.

The poacher hesitates.

Then he swings the barrel towards Hitoshi instead, and Denki’s stomach plunges deep into the cold of the sea.

Around them, the merfolk burst into uproar.

The man backs towards the other side of the boat, keeping his aim locked onto the long, bared line of Hitoshi’s throat, only jumping slightly when the siren lets out a warning hiss around the gag between his teeth. There’s fear in the poacher’s face but it’s not the kind that Denki can work with. It’s ancient, marrow-fear, prey-fear. A hysteria that heralds stupidity, poorly disguised as survival instincts.

“You don’t see it,” the man stammers. “They’ve—they’ve got you brainwashed, you just don’t—”

He gasps as the boat begins to tilt, gradually angling the deck down to the starboard side, and scrambles towards the opposite. Several of the others aboard, still cowering and clinging, shout at their companion to lower the weapon as the boat then rocks back in the other direction, causing a few to slide across the deck in open panic, grasping for anything that will keep them out of the water, out of the hands of the man-eaters from their old folk tales below.

Denki can feel the rage of the colony as clearly as if it were his own, but also understands the fear of his fellow humans, faced down with that which they’d considered impossible, having fallen too deep to get out on their own.

The sides of the boat creak in warning as it rocks to the starboard again, urged on by magic. The next time it dips, he swears he sees something on the far side, hidden just below the railing.

Red eyes on black, darker than the night.

It should terrify him, but instead he feels relief.

“Wait—wait,” he calls out, then repeats the word louder in Mermish, and the boat evens out.

Denki reaches for the railings of the other craft above him, and drags himself upward. Bakugou and Uraraka both immediately protest it, because of course they do, but there’s only one way he can think of to keep the others alive. They seem to see this, and with a grunt, Bakugou helps ease him over the bars, mindful of the makeshift splint on one calf. Pain lances down his injured arm and up his leg regardless when they bump the rails, but he pushes it away. Far away. Not important right now.

He straightens up slowly, hands raised to show his lack of weapons, even as his heart pounds still seeing the gun trained on Hitoshi. “Easy,” he says, forcing a small smile. “There’s no need for more violence today, y’know? You don’t need to follow in your head honcho’s footsteps.”

The man’s hands shake. “Giran,” he murmurs. “He’s—dead?”

Denki swallows. “Yeah.” He sees the flash of fear and the gaze that strays to Hitoshi again, and quickly adds, “It wasn’t one of them. It…” He swallows quickly. “It was me.”

Perhaps he shouldn’t be relieved by the rifle swinging from Hitoshi back to himself, but here we are. He notes the half-formed question shaping the poacher’s lips, and waits. The man is faltering. Denki clings to hope.

Finally, “You gonna kill me, too?”

“No,” Denki replies swiftly, sharply, nausea rolling through him. “Didn’t… shit, didn’t want to—to hurt him either, buddy, but it was either destroy that ship or live with letting him m-murder everyone still in the water. Mer and human both.”

He watches the man’s throat work around a heavy swallow. The gears clicking and turning behind the poacher’s eyes gradually get the job done. “The ping?”

Denki nods tightly.

The man wilts, shifts his feet. The gun doesn’t lower, but the prey-fear is receding just enough that Denki can see each consideration crossing the guy’s face in real-time. “He said the ley-line was open for taking, no mention of about all the legends being real, we didn’t expect… but then…” his gaze drifts back to Hitoshi, who has ceased growling and simply stares right back, heavy-lidded but intense.

“We came out ‘cause he said it would be worth our time,” a kneeling woman adds from off to the side. “Told us you’d try to trick us with illusion magic so you could keep it all yourselves. But that—” she points at Hitoshi. “—ain’t an illusion. Told us to take it with us and he’d deal with it later.”

“Well, he won’t be doing that anymore,” Bakugou mutters loudly enough for the deck’s occupants to hear.

Denki takes a few careful, hobbling steps towards Hitoshi. “He’s as real or you or me. Let him go.”

But as he raises his hands to the ropes, the man with the gun fixes his trembling grip in warning.

“Don’t. Don’t,” Denki insists, voice far steadier than his hands as licks of lightning dance across his arms in tune with his pounding heart. Even under his command, the magic has a mind of its own; he makes sure to keep his hands pacifyingly open as stray bolts quiver and snap down towards the damp deck, but the poacher’s eyes track the crackling light with undeniable fear. Denki holds it steady, keeps it under rein, until the sensation is a mere constant prickle along the surface of his wetsuit. “There’s nothing good down that path, alright? This is your out. Please, take it.”

From all around the boat, he hears a single word passed around the crowd of mer like the gentle whisper of a tide breaking on sand: Zyaroshii. He can’t make out whether the hiss feels more reverent or threatening.

“Our ‘out’?” the man repeats, voice quaking. His face losing the rest of its color in the dim light. “They’ll sink us as soon as he’s off the trawler!”

Denki takes a deep breath, counting to three. “Think it through, buddy. Take a minute, if you need to. What’s stopping them from already having done that? Of everyone on this boat—” He points his thumb in Hitoshi’s direction. “—only one of us has gills.” He takes another step forward, lowering his voice, eyes never leaving the poacher’s. “You’re gonna need to take my word for it, okay? If you let him go, we’ll come to an arrangement that’ll get you home. But if you take a shot at him? I swear on the gods, on Chaos,” he whispers, letting the lightning halo his hair and spark down his throat, “It’s not drowning you’ll need to worry about.”

That seems to do the trick.

The man backs against the far rail, rifle wavering but hesitantly tilting skyward as he nods.

Denki wastes no time, pulling his knife free and sawing at the ropes. Almost as soon as Hitoshi regains use of one arm, he yanks his gag free and immediately tugs Denki’s forehead against his own for a split, intimate moment. There’s unspoken wonder in the depths of the siren’s eyes, a tidal wave of questions and disbelief and magic pressing against Denki’s own, testing it—then Hitoshi turns his stare back to the poacher.

…And beyond. Denki feels the shared prickle of unease and yet isn’t fast enough to stop Hitoshi’s fins from flaring as the siren lets out a testing, anxious hiss.

Misunderstanding, the poacher startles and swings the weapon’s barrel down again—only for it to be caught in a broad, gray-black palm from behind.

Aizawa yanks the gun free and tosses it over his shoulder, where it vanishes for good with a quiet splash. He stares at the human beneath him, expression not changing one bit when the man’s knees buckle and fold him to the deck with a whimper. Instead, the older siren’s red gaze slides right back up to land on Denki, and he lets out a long sigh.

“That’s good, kid,” he rumbles, the deep, even timbre of his words blessedly familiar even with the vocal warping of different anatomy. He looks to his son, slow-blinking until Hitoshi, too, sags back with relief into the remaining ropes keeping him tied. “It’s done. It’s over.”

The end of the fight doesn’t feel real. For all that it’s been only half a day since they’d first taken up arms, Denki can’t seem to shake the on-edge feeling that something will inevitably go wrong with the resulting peace talks. Maybe it’s irrational, maybe it’s not. He doesn’t know nearly enough about politics or diplomacy to wrap his head around what needs to be ironed out for the safety of the colony; he’s a mechanic, for gods’ sake.

So he focuses on what he can handle: cutting Hitoshi down and letting the siren check over him with careful hands and barely-there croons, murmuring ‘it’s alright’ and ‘I’ll heal’ each time his mate catalogues a new bruise or gash. He can still feel the questions about his newfound magic buried just under the surface, but it’s not the right time, not when the high is fading and the last few hours are catching up to him both mentally and physically. The breaks are the worst of it. When his adrenaline finally clears, the pain returns with a vengeance, and it takes both Bakugou and Uraraka to help him from the captured vessel back to the comfort of the Midnight Lady.

Hitoshi is clearly torn, wanting to stick close to Denki’s side but also knowing his duty in dealing with the mess at hand. So, Denki has to manually override own his immediate concern that letting the siren out of his sight will be permanent this time, and shoo him off to get the recognition of his efforts among the colony that he deserves. And an apology from them, hopefully.

Then, once Uraraka has patched him up to her satisfaction and he’s left alone, he finds himself unwilling to go below deck to rest just yet. The first breath of the dawn ghosts the sky to the east as he settles into one of the captain lounge chairs on the stern.

It gives him a front-seat view to the sight of Yamada nearly tripping himself down the stairs from the upper deck with a shout, splotchy from tears but grinning as wide as his cheeks will allow when the long black form that is Aizawa gracefully eases himself aboard. They come together as if magnetized, buried in each others’ grip, words passing between them too low and muffled for Denki to overhear. He sees the shaking of Yamada’s shoulders and reminds himself to give them privacy, turning his attention back to the sea.

The rest of the mer are rounding up the remaining poachers and their boats, firm and glaring but making no further move to fight. Only a few among the humans need restraining; the others, judging by faces, are everything from cowed to resigned to awed as they await a more docile fate.

Denki’s gaze finds the large golden coral mer, engrossed in stiff conversation with both Hitoshi and the flame-patterned siren. The latter has aggression in every line of his bulky form, fins angled back and brows pressed low as he glares down at Hitoshi with clear disdain. Hitoshi, so small between them, loses no ground with pinned aurals of his own and something clearly sharp on his tongue.

It’s enough to pique Denki’s worry. Everything alright? he pushes, hoping the feeling behind the words will suffice.

Hitoshi pauses and glances over his shoulder, directly back at the Lady, and finds Denki with his dark gaze. The movement reveals Eri held against his chest; she too follows his stare. He turns back to the others for a split moment to say something—then they’re all making their way over to the boat.

“Uh, hi,” Denki mumbles when they’re finally within range. It’s hard not to cower under the glare of the fiery one, so he looks to the others for context instead. Belatedly, he wonders if his current predicament—one leg propped up and iced, forcing him to recline almost lazily—could be seen as disrespectful. He winces and tries to shift.

But the golden one raises a large hand. “Rest, young one. You’ve done enough. We were simply discussing what will become of the rasyakiin, and welcome any thoughts you may have on the matter.”

Denki swallows and glances out towards the herded boats. It’s hard to get a feel for how many are left, compared to how many were…

Hitoshi’s hand finds Denki’s good foot and squeezes lightly, cutting off that line of thinking.

He clears his throat. “They’ve surrendered,” he points out. “There’s no reason to hold them, but please don’t kill them. I know my word might not mean much, and I shouldn’t have spoken for you all, but…”

“Your word is as good as any one of ours,” the golden says, smile broad and more reassuring than Denki knows what to do with. “Taking their lives is not being considered.”

The deepening of the navy-and-flame siren’s scowl suggests otherwise, but he doesn’t protest, simply muttering something lowly in Mermish that Denki can’t make out.

“Then… what?” Denki clarifies, worry abating.

It’s Hitoshi who hums next, looking down at Eri first then meeting his mate’s gaze. “Ah… memory,” he says smoothly. “Change memory, some. To forget. Others…?” He says something in Mermish, looking at their golden ally.

The larger mer nods. “I understand that one among your pod has a talent for negotiating pacts with humans. Some rasyakiin wish to make amends with goods and services and connections, to help rebuild. Her magic will hold them to their word.”

Nemuri, no doubt. Denki thinks he sees her standing on one of the vessels further out, backlit by the sunrise. He’s glad she’s well enough to do so.

“And others will be bewitched to forget,” he murmurs. “That’s… more than fair.”

“They will bear the news of their brothers and sisters lost in a sudden storm,” the golden one says. His stark blue eyes aren’t cold, but hold no hesitation as he adds, “And will spread word of the unexpected colony who sent them safely back to shore.”

Denki straightens with surprise. “You’re going public? Already?”

He’s met with another unnatural but genuine laugh. “The dark one assured me that, ah… ‘documents’ to protect the grounds have been made and passed along to those who need them. It is only a matter of time. And if I may be direct…” the scales at the mer’s eyes crinkle with amusement. “We have waited long enough as it is to reclaim our identities. We belong in more than just your… what did you say? ‘History books and fairy tales’.”

Denki’s throat tightens as he’s hit with a complicated wave of second-hand pride. “Yeah,” he chokes out. “Gods, yeah. You do.”

He can’t see the gentle smile clearly through the sudden wetness of his eyes, but knows it’s there, as the merman continues lightly, “We owe you the greatest of debts, Zyaroshii.”

Denki takes a breath to steady himself. “Zeea—what does that mean?” he finally asks when he’s able to see clearly again. The flame-patterned siren had slipped away during his moment of weakness, it seems, but Denki doesn’t mind that one bit.

Hitoshi, too, is staring at the golden one in shock.

The older mer looks up at the now-sparse clouds. “We felt when little Eri shared her strength with you. We saw what came next. She called the clouds, just like her forbearer… but gave you the blade to fight for her purpose.” He raises one long arm, reminding Denki of his own motion back then—and then smiles. “Zyaroshii. It is ‘the one who wields the storm’. Your magic is her gift of trust in you, and thus the trust of all of us, as well.”

Eri, either in agreement or simply pleased to hear her name, chirrs delightedly from the crook of Hitoshi’s arm.

Hitoshi—who stares back at Denki in a new light. “Magic? Is… is yours? Forever?” he asks, something quiet and hopeful in the soft words.

Years past, it had taken concentration and notable effort for Denki to draw on his limited affinity even when he’d flaunted it from day to day. Like most humans, channeling it had been a matter of sigils and careful preparation. He expects that again now that he’s expended so much of it, but instead takes himself by surprise when barely a thought has sparks jumping between his lifted fingers. It’s fascinating. Nearly frightening. But most of all—

He faces Hitoshi, and the sudden rush of longing and excitement and desperation bouncing between them like an echo chamber drowns out the rest of the world in an instant. It claws its way into Denki’s lungs and heart and anchors itself there, a placeholder for something as important as breathing that hadn’t been possible, but now is. 

Hitoshi lunges for the rails and struggles to pull himself up over them with one arm around Eri, heaving himself bodily onto the deck with a grunt. It’s awkward and inefficient, and Denki wishes more than anything that he could get up to meet his mate, but—

“Wait,” a deep voice calls out.

Aizawa.

It’s enough to stop Hitoshi, because of course it is, though when he turns to face his adoptive father it’s not without a hesitant, guarded look. He slowly angles himself between the massive dark adult siren and Denki, indicating his attention with an even stare and a flick of his aurals.

Denki sees the moment that the behaviour makes Aizawa falter, catches the flicker of hurt across the man’s changed features and the brief moment of resignation that follows it.

Behind the siren, Yamada winces, no doubt feeling everything that runs through their bond, but far less capable of schooling his far more expressive reactions into neutrality. “Hitoshi…” he says weakly, as if pleading on his other’s behalf, but is met with a quick, barely-there shake of Aizawa’s head.

“It’s… justified,” the adult siren murmurs, and his gaze raises to Denki, searching but unreadable.

Just as before, a small part of Denki argues that he should be afraid—but he’s not. There’s a world of difference between the feral half-shifted man who’d torn at him in the cave like a wild creature defending its young, and the calm but many-times-more-dangerous being watching him now. Though the scales and horns and jagged teeth are new, Denki can feel the steady warmth of the man he’s familiar with coming through.

So he offers a smile, an olive branch. “That wasn’t really you, sosvii.”

If Aizawa is affected by the thinly-veiled forgiveness, he doesn’t show it beyond the subtle relaxing of the line of his shoulders. He leans forward further, and slowly reaches out towards Hitoshi with both hands.

After a moment of consideration, Hitoshi’s aurals relax and he hands Eri over to his adoptive sire.

The single act bleeds most of the tension from the family standoff. Eri lets out a pleased chirp as she settles in the crook of Aizawa’s arm. She clings to him like a toddler to a favourite parent, curling into his sturdy chest and immediately distracting herself with a long section of dark hair.

It takes another few seconds for Aizawa to speak, but when he does, it’s measured. “If you could wait to bond until everything has settled, when you’re healed again, I have… a proposal that may interest you.”

Denki’s heart sinks at the idea of waiting even longer – it feels like it’s been eons and not a matter of days since that first journey down to the heart, when he heard the whispers of different paths laid out before him and brushed Hitoshi’s thoughts for the first time. He meets Hitoshi’s over-the-shoulder gaze and feels the soft frustration and impatience within him. Their connection is different from then, something in-between mate-bonded and not, but they could be more. Denki wants it more than anything. And he’s right here, ready for it.

And yet… Aizawa knows that, doesn’t he? He supports them. He wouldn’t interrupt this moment without good reason.

Denki swallows and tilts his head. “Yeah?”

Yamada moves to kneel next to his mate. Normally the lankier of the two, he now looks small next to the siren’s full length, as if the picture of the pair Denki has kept in his mind has become fractured and warped. The melancholic expression on his face as his eyes trace the tail of dark scales coiled beside him only adds to the strange weight of the sight.

Denki supposes a hundred years of familiarity with one shape would lead to anything else being an odd fit.

The pair across from them share a moment with locked stares.

And at last, Aizawa sighs, his gaze wandering down to the girl in his arms. “This form is no longer who I am.” He cradles Eri to his chest, thick hair falling over his shoulders as he tilts his face down to meet her outstretched hands. He makes a small, amused sound when her fingers brush curiously across the tattered edges of his aural fins. “I didn’t want it back, but… the tides have their reasons. Something compelled Chaos to keep calling, no matter how hard I tried to ignore it. It was irrational of me to think I knew better… magic always returns to its source eventually. In this case, the sea.”

Perhaps it’s the lingering pain or exhaustion catching up with him, but Denki struggles to follow. He nods anyways, glancing down to Eri. It seems as if her curiosity has subdued somewhat; the expression she wears as she listens to the onyx siren speak is a new one, like understanding and relief and inexplicable pride all rolled into one, leaving her seeming far older than her young form would suggest.

Aizawa turns the hand that rests along the small royal’s side palm-up, like an offering, and Eri’s tiny fingers move to it. She wraps around his large, clawed thumb like a favourite toy, traces the lines of his webbing, and taps the harder scales on the back of his knuckles with great interest. Finally, she lays her palm against Aizawa’s; the tips of her fingers don’t even reach the base of his. Chirring under his breath, he curls them gently over the top of her hand.

The siren’s gaze drifts up to his softly-smiling mate, and then to Denki once more. “I can feel a difference in Chaos’ hold, and Eri’s conscious magic is stronger than that of the Heart. As such, I… believe I now have the opportunity to leave this form behind for good.”

“Okay,” Denki replies after a few seconds of silence, unsure. “That’s—that’s good then, right? I mean, congratulations.” Had he missed the ‘proposal’ part in there, somewhere?

Aizawa hums what might be a thank-you, and lifts his free hand to scratch at his jawline, the tight line of his lips betraying that there’s something else as he holds Denki’s gaze.

“Kid…” he takes a deep breath. “Chaos magic can’t be created. But, as you’ve learned, it can be stolen. Lent, traded.” He pauses. “In the right circumstances, even given away. Permanently.”

In front of Denki, Hitoshi suddenly sits bolt upright and still as stone.

Aizawa continues, voice and eyes both softening. “And… logically… there’s no reason for mine to go to waste.”

It’s not stated like a question. It isn’t.

But Hitoshi makes a punched-out, hopeful sound and apparently has to steady himself against the deck—

—then promptly has to steady Denki when understanding hits and the universe tilts violently along their mental connection. At the physical contact, Hitoshi’s thoughts flood into his, and the siren’s shock and disbelief are so thick that Denki struggles to wade through them in order to locate his words.

“You don’t—you can’t possibly mean—” His mouth is dry, so dry. Denki indicates towards the adult mer’s thick, dark-scaled tail, the fins, the gills, all of it, with a shaking hand. “Th-that I—that I could be—?”

The corners of Aizawa’s mouth pull up, just barely, giving in to the warmth that’s already clear in his half-lidded stare. “Yes. If you would continue to protect her.” He nods down towards Eri. “And if you want it.”

The question itself has never been in the cards before. It’s never struck him as a possibility. And yet, without so much as a conscious thought, Denki knows that every atom of his being has hummed with the desire since the first time he saw Hitoshi on the shoddy cameras of the sea rover. Or… perhaps longer back still, when he’d chased Chaos deep into the earth, reaching for something that he’d only ever known in dreams. Something that didn’t belong to him.

Yamada grins from ear to ear; Eri watches Denki with a small smile and knowing chirp. And Hitoshi, oh, Hitoshi, he turns with the most fragile, wide-eyed expression he’s worn in all their time together, like one wrong breath is enough to take him apart in ways that he’ll never piece together again. He lifts his fingers to Denki’s cheek, brushing them over—oh. Tears.

“…Denki?” his mate whispers uncertainly.

There are so many ways to say yes, please, and yet what finds its way out of Denki’s lungs is a shuddering sob as he stares at the people who are offering everything he wants and needs with expressions that say he deserves it.

He’s down on the deck in Hitoshi’s arms in an instant, nodding rapidly into the crook between the purple mer’s shoulder and neck as every bit of leftover fear and adrenaline from the fight spills out of him at once. Hitoshi’s hardly able to keep a cap on his own low noises, and Denki’s sure he hears Yamada break into happy sobs of his own with a quiet, ‘Oh, Shou,’ nearby.

Eri chirps, and he feels her tuck up against his side. Then there’s a steady hand on the back of his neck, low murmuring that could be either Japanese or Mermish or both for all he’s able to focus on it, more arms bracing them from all sides—and Denki has never felt more like he’s belonged somewhere in his life.

To be at Hitoshi’s side for real, to be a mer—he can barely wrap his mind around it, but knows he wants it with every atom of his being.

“How soon?” he manages to croak out after an indeterminable amount of time, rubbing at his eyes with the back of his hand.

Aizawa pulls back from where his forehead had been pressed against Yamada’s above them, aurals flicking as he glances first at Denki then out over the water. He hums. “Once the trench-dwellers and the rasyakiin leave. Once the corals are settled. Once you’ve healed.”

It’s a lot of conditions. It could be weeks of waiting.

But they have all the time in the world, now, Denki knows.

He laughs wetly, and smiles at Hitoshi, who grins back at him with settling familiarity. Serene. Confident. Endlessly, unquestionably enamored. The adoration in his eyes shares the clarity of the now-cloudless dawn sky.

“That’s worth waiting for,” Denki agrees.

Chapter Text

It takes three nights for the trench sirens to decide to go home.

It could have been sooner, in Hitoshi’s opinion. Should have been sooner, except several of the adults among them had continued to gnash their teeth at him dawn after dawn, putting out various loose, unsatisfying reasons as to why Eri should be given up to them. Safety in segregation. Preservation of the ancient ways. Because those who’d given up their songs once couldn’t be trusted not to do so again, they insisted.

First, he’d laughed at the suggestions. But when they didn’t cease, he’d bared his teeth at the lot of them, fins prickling and the healed wound on his abdomen aching with memory of the last time he’d held his own against the opinions of his old colony.

≈She’s safe with us,≈ he repeats again now, trying and failing to keep enough distance to not hurt his neck as rhoya Enji looms over him. Hitoshi angles his torso away defensively, resisting the urge to hiss and spit like a fearful hatchling, and instead levels at the flinty councillor’s the most dead-eyed stare he can muster.

The councillor’s top lip curls in disdain, vibrant eyes colder than the trenches themselves. ≈You can’t even protect yourself, outsider,≈ Enji cuts back in a low voice. The label gouges deeper than expected, a formal but branding reminder. ≈From neither walker nor our kind. That does not inspire confidence.≈

Hitoshi’s claws curl into the meat of his palms, pinching skin to keep him steady. Excuses weigh heavy on the back of his tongue, twisting like live eels down his throat to his belly. ≈I don’t owe you confidence. I don’t owe you anything.≈

He dodges briskly under the rhoya’s thick arm, feeling the heat-magic that surrounds the other at all times. He hears the growl Enji makes at the show of disrespect, feels displaced water as the length of the other lashes around and a broad hand chases him for it—

≈There you are, Hitoshi.≈

Hitoshi’s heart stutters back to life in his chest and he propels himself to sosvii Aizawa’s side, trying to calm the rapid expanding of his gills. Keeping his back to the rhoya makes his skin crawl, but he can’t bring himself to look back when he’s trying to play it cool. It takes conscious thought to stop his aurals from pinning, and he feels sosvii’s suspicion through the pod bond, edged with faint alarm.

He rolls his shoulders back. ≈The rhoya and the others of the trench are leaving soon,≈ Hitoshi clarifies loudly. ≈I assured him, again, that we’re equipped to take good care of Eri.≈

Aizawa responds with a contemplative walker noise, distorted due to lack of air. ≈Your concern is noted, Enji. But unwarranted. You’ve fulfilled the colony’s debt. We can do the rest.≈ He places a hand on Hitoshi’s shoulder. ≈We’re needed. If there’s nothing else?≈

The navy and orange mer fixes Aizawa with a glare like a volcanic vent, then turns and launches himself off in the direction of the colony grounds without a word.

Hitoshi shakes out the remaining tension in his arms. ≈Thanks.≈

≈He doesn’t know how to leave it well enough alone. He’ll be gone soon.≈ His assessing gaze skips down over Hitoshi’s briskly. ≈Are you alright?≈

≈Yeah. It was all, y’know. Posturing.≈ It almost wasn’t, but Hitoshi isn’t going to dwell on near misses. This kind of thing just comes with the half-breed territory. It wouldn’t be a problem soon enough. ≈Nothing new. Though I thought maybe everything with retrieving Eri would have made them reconsider my place in their eyes.≈

Aizawa arches a brow. ≈You want them to consider you a part of the trench colony again?≈

≈Nah,≈ he answers honestly. Then he clicks with irritation. ≈But it’s like they forgot that they’re the ones who stabbed me.” He feels sosvii’s grievance building at that reminder, and waves it off. ≈You said we’re needed?≈

His podsire side-eyes him, aurals flicking mischievously. ≈Mm. A… rational deception. You were distressed.≈

Hitoshi imagines burying himself in the sand. He’s touched, really, but at times still forgets that there’s no deceiving the pod bond. Sosvii had seen right through him.

So, setting that aside, he clears his throat and changes the subject. ≈The corals and most of the hybrids are opting to stay to rebuild,≈ he explains. ≈Eijirou and Mina say that rhoya Toshinori’s presence has convinced a few of the sirens, too. And… also several of who’d given up their fins before. Like you.≈

Sosvii makes the walker sound again—a hum, Hitoshi thinks it’s called. Apparently it’s his way of acknowledging a statement but offering no further commentary, which is not a satisfying resolution to the conversation Hitoshi wants to have but can’t for the life of him figure out how to start gently.

So he takes the straightforward approach. ≈You haven’t reconsidered giving up your magic?≈

His podsire’s aurals flick up with amusement and he tilts his head to suggest they go for a swim. ≈Do you want me to reconsider?≈ he asks, a sly lilt to his tone.

≈What? No.≈ Hitoshi feels the prickle of magic and warmth through his skin, and can’t stop the faint glow of the luminous spots on his face and neck. ≈No, of course not, it’s just that it’s… a big deal.≈

He watches the way sosvii navigates the water gracefully, as if the other hadn’t spent half a lifetime in a walker’s short, fin-bare body. It’s a reminder of what Hitoshi himself was ready to give up, of how he’d privately resolved to take the same deal as sosvii before him to join Denki on the land, on some future far-off moon. He’d have done it, eventually.

But now he doesn’t have to.

He catches up with sosvii, gliding along beside him. ≈I’m… grateful,≈ he continues quietly. ≈Just thought you’d miss this now that you’ve had it back, is all.≈

Aizawa is quiet for a moment. Then, ≈I will miss it,≈ he says. ≈But not in the way I did before.≈

He leads them deeper, towards the center of the colony grounds. Already, construction is underway all around the ruins of the old settlement: on the left, one group is gradually building clay and stone and other materials into rounded walls; on the right, a completed dome structure is being hardened through magic by a pair of adult corals Hitoshi doesn’t recognize. Still, they wave at him with broad smiles as he and sosvii pass. Recognition is an odd experience. He waves back hesitantly.

Beside him, sosvii hides a grin beneath a hand, aurals flicking up once again.

To spare himself some needling commentary, Hitoshi quickly revives their talk. ≈What’s changed, then?≈

Aizawa rolls his shoulders forward slowly in the same way Denki does when he’s unsure of an answer. ≈Mm. Before, ‘missing’ it was… out of my control. The first time, I’d been left with just enough magic that the Chaos within me paced restlessly I thought that distancing myself from the sea would calm it, or make it wither away altogether. My logic was… flawed. This time, I’ll ensure that it’s done right.≈

Hitoshi accepts the explanation with a quiet chirp, though he can’t help but fidget as a more pressing question builds. He lifts his fingers to the back of his neck with a small frown, glancing away. ≈What about your current bonds? Like to sosvii Yamada.≈

Though he doesn’t say it, the ‘and to me’ sits at the forefront of his thoughts, clear as crystal.

A sudden touch to his nearest shoulder makes him flinch, but it’s just Aizawa’s broad hand settling there again.

Hitoshi side-eyes his podsire hesitantly at first, unsure of what kind of pity or apology he’ll be faced with. He doesn’t want to hear that the bond will cease to be, and worse, doesn’t want to see it in sosvii’s expression—

But when he’s met with a soft, deep-chested rumble of reassurance and a subtle, warm smile, he figures he’d assumed wrong.

Hitoshi responds in kind and leans into it, relaxing when Aizawa’s touch slides over to ghost along his thoracic fin. There, the brush of sosvii’s magic says everything that his words do not. It’s a soft weave of security, and a promise that neither the sky nor the deep will ever come between him and those he’s tied himself to. Hitoshi rests his head against Aizawa’s shoulder and closes his eyes.

≈The bonds aren’t going anywhere, guppy,≈ sosvii murmurs.

The shared magic, never deceitful, echoes his sentiment.

Hitoshi smiles.

“Iri kiir de… shavaar e…  asa-assay—”

“Asaeriik,” Yamada corrects slowly, drawing out each syllable with the patience of a saint. “You’re getting closer, kiddo! If you flatten the vowel a bit more you’ll be spot on.”

“Right,” Denki says, slumping in his seat. “Yeah, a bit more. Got it.”

It’s a lie. He absolutely does not get it, not by any stretch of the imagination, struggling more and more with each attempt to hear the minute differences between his own pronunciation and Yamada’s. Not for the first time this week, he comes to terms with the reality that he’s going to butcher this phrase beyond all recognition. It’s only raw determination that keeps him at it, twisting his tongue into all sorts of new, frustrating shapes in the struggle to imitate Mermish.

Yamada’s quirked brows and wide grin read as understanding, if also a bit pitying. That’s fine. Totally fine. He’s the one person Denki’ll deign to accept the pity from—shared experience, and all. He knows. Been there, done that.

“Perhaps you should stick to Japanese. Hitoshi will understand,” Aizawa contributes from the far sofa, and ouch. There’s a confidence killer at its finest.

Yamada clucks his tongue. “Shouta! It’s meant to be romantic!"

Denki feels the flush rise from his neck to the tips of his ears.

Aizawa’s huff in mer form comes with a rumble like a big cat chuffing. It’s weaker than it was an hour ago; if the man’s scales weren’t already mostly monochrome, Denki wonders if he’d be going pale. It isn’t the first time the mer has smuggled himself into the belly of the boat to evade talking to the great golden coral Denki’s come to know as Toshinori, and probably won’t be the last.

“I’m going to have to learn how to pronounce everything anyways,” Denki points out, rubbing at his face self-consciously. “These words are just… important ones.”

Aizawa ignores Yamada’s coo of delight, arching an eyebrow. “The vows are antiquated—”

“—They’re romantic—” his mate insists.

“—but if you’re going to insist on them, perhaps wait until you can use the language properly.” Aizawa shifts with a wince, the end of his tail and its dark fins spilling across the floor as he props himself up against the arm of the sofa with his elbows. “Learning the sounds wrong won’t get you anywhere.”

Beside Denki, Yamada likewise straightens up where he sits. There’s a dangerous glint to his narrowed stare. “I beg your pardon? ’Wrong’?” he asks, voice deadly even.

Aizawa meets his mate’s stare without flinching. “…Yes?”

Denki suddenly gets the notion that he should be seeking shelter. Or perhaps another boat altogether. He mumbles an excuse to struggle to his feet under his breath, mindful of his crutch and braced ankle, packing up the few notes scattered about with barely-contained urgency.

Yamada utters something in Mermish—too quick and too complex for Denki to grasp, but the sharp-edged tone of his words leaves no room for doubt. Then, more carefully, he forms the very phrase that Denki’s been studying for the last few days: “Iri kiir de shavaar e asaeriik sho’alor irim syare daransuiir.”

Denki can’t help himself, pausing to look up at sound, so delicately-shaped and lyrical. It sounds incredible, like every bit of Mermish he’s learned from the pod thus far, something both foreign and familiar and full of life.

He watches the small smile that curls Aizawa’s lips, and the amused flare and flick of the mer’s aurals. Then the siren repeats it, slowly and softly, and—

It’s absolutely not something human vocal cords are able to replicate.

Yamada throws his hands up in exasperation. “That doesn’t count, Shou! Biology notwithstanding, it’s as close as possible, and you know it.”

The mer gives a one-shoulder shrug, his lazy grin showing off long, sharp teeth. “Sure. But ‘close as possible’ is still wrong.” His red gaze shifts, reining in some of the playfulness. “It’s fine, kid. Remind me closer to the ceremony and we’ll work on the details.”

With a shake of his head, Yamada sighs, before turning his own attention away from his mate and back to Denki. “But just to be sure, you remember what it means?”

“Of course,” Denki replies. The phrase has been gracing his every Hitoshi-related thought since he first learned of it last week. The words fill him with a sort of reassurance, a rightness, like the missing piece of a puzzle, or a token of good luck. He smiles. “It’s—”

Humans are exhausting.

One would think that after decades of carefully-detailed pacts and a carousel of eager volunteers seeking magical highs in exchange for… temporary subservience, well, that one might also be used to dealing with the uniquely human brand of impatience.

This is not the case.

They rush and rush, stress about deadlines and dues as if the sea will be gone when they wake up in the morning. The thought of open-ended debt and favors makes them sweat, apparently, which while vastly entertaining also means that Nemuri’s been working out and marking down obnoxiously specific owings for days on end now.

She stands with a sigh and runs her fingers through a strung canvas of small jewels, each one a debt or pact collected from different rasyakiin in the three weeks since the end of the conflict. They clink against each other gently, the magic of them resonating with her own, a chorus both for her ears and her soul. In truth, it’s an honor to be the keeper of these pacts on the new colony’s behalf, providing this small service to aid in the efforts for peace and rebuilding – and the sooner the humans move along, the better.

The complex magic-weave of the wards, spells, and artefacts around her room shift in response to a more familiar human passing through the open doorway; she doesn’t need to turn to know who it is. The unique magical signature that sings of emerging sunshine and soft ukulele-song is Hizashi’s, through and through, at this point almost as familiar as her own. Even without a proper pod-bond, she can feel his curiosity reaching out to her, and beyond her, to the tapestry of glittering stones.

“Woah. You’re building quite a collection there,” Hizashi says, stopping a few feet away. “Those all from our new… acquaintances?”

Nemuri chuckles, drawing her fingers over them again, each hitting a different note that only she can hear. “Sure are. Some given willingly, some… needing a little coercion. But a sacrifice far more palatable to them than the alternative, as was made plenty clear.” The rest of it goes unsaid as she reaches for a bottle of sake, pouring them each a glass. “How is Shouta?”

Hizashi draws out a thoughtful, high-pitched hum, ending it with a weak shrug and half-smile. “Getting impatient. I’d say it’s not like him, but honestly... it feels sorta like the old him. In a good way.” Half-smiling, the blonde sucks on his lower lip and falls gracelessly into the chair at Nemuri’s decorated vanity. His gaze tracks to the porthole on the wall and his fingers beat a tuneless tempo on the bony curve of his knee. “Y’know, he keeps going on about taking a long trip inland and staying there ‘til we’re old and gray. Sorta like he used to, for all he says he’s not going to make the same mistakes.”

“He won’t,” says Nemuri. She offers him a glass.

“He won’t,” Hizashi agrees, flashing a grin as he accepts it. “But I’m letting him believe his own bullshit for now.”

Nemuri snorts. “He may be freeing himself from obligation to the sea, but he’s kidding himself if he thinks there won’t be something pulling him back.”

“One might even say three somethings.”

“Or more. I saw him eyeing some of the other young ones just yesterday. I think he’s starting to collect them.”

“Oh, lovely,” Hizashi says, his tone perhaps trying for ‘exasperated’ but instead falling solidly into ‘fond’. The corners of his eyes crinkle with excitement. “I’ve always told him he’d make a good dad.”

“And the ones who haven’t spent time around humans will need a teacher. Or teachers, plural.”

The blonde arcs a thin brow, but his smile doesn’t waver. “Mm. Plural sounds about right.” He raises his glass, holding it expectantly. “To teachers?”

Clink.

“To teachers.”

“I’m impressed—this is a lot faster than we expected, even factoring magic in. The colony’s healers did a really impressive job, Kaminari. I think your ankle’s as healed as it’s going to get.”

Uraraka pulls away from Denki’s outstretched leg, letting him flex it back and forth.

Finally liberated from the ungainly cast it’s been in for nearly a month, it’s stiff enough that it smarts and makes him wince when the muscles protest. But beyond that, there’s no deeper pain. He doesn’t remember the last time it’s been that way—years, at least. It’s almost surreal.

The sudden uptick in his heart rate is due to a completely different reason, however.

“I’m healed. That’s it then,” he says, trying to keep his voice steady. “That’s all of the conditions met.”

His words are met with silence; he glances up, seeing the confusion written clear across both Uraraka’s and Bakugou’s faces in squinting eyes and shifted brows. One kindly curious, the other irritably expectant.

And just like that, Denki comes to one very, very important realization: he forgot to fucking tell them.

“Oh,” he says faintly, staring down at his legs. “Y-yeah, yeah, I didn’t mention, hah.”

“Didn’t mention what?” Bakugou pushes, voice challenging. Although Denki can’t see the other blonde’s face, he watches Bakugou’s calloused fingers curl almost threateningly around the edges of the cut-off cast.

Denki clears his throat reflexively. “Nothing bad! Actually it’s… really exciting? So, um. It’s just that… uhh. Well. We’ve found a way to make it so that Hitoshi and I can stay together. Without uh, biological differences getting in the way.” He can’t look up, can’t make himself see their reactions as his mouth keeps moving. “Buuut Mr. Aizawa asked us to wait for three things to pass first—the conditions I mentioned, yeah? The hunters leaving, the colony settling, and,” he gestures to his legs with a nervous laugh, “…me getting better.”

Uraraka’s hand settles over his. “You mean Hitoshi is going to do what Mr. Aizawa did? Leave the sea for you? Wow, Kaminari, he must really love—"

“No! No,” Denki replies, voice strangled. “I mean. He would have, I think, I know he—but that’s not—it’s. Uhh.” Another laugh bubbles up from somewhere deep and anxious. “It’s… the opposite, actually.” He swallows thickly, trying to steady himself. “Mr. Aizawa is going to give me his magic. He thinks Eri can make it happen.”

There’s a long moment where the silence seems to stretch on like the sea at the horizon, and Denki can feel the weight of their stares, but can’t meet them. It’s only when Uraraka’s hand tightens on his and he hears a watery giggle that he instinctively glances upwards.

The worry clutching his heart releases at her teary eyes and wide smile. “You dummy,” she says softly. “You say it like it’s a death sentence. Do you really think we wouldn’t be happy for you?”

Speechless, he glances to Bakugou.

“Fuck,” the other blonde swears under his breath, then shakes his head and laughs. His voice is strained. “You idiot. It’d be stupid for us to be upset, though why you’d wanna live in a hut underwater is beyond me.” He pulls a face, brows creasing with some delayed realization. “I won’t be able call you ‘creaky’ anymore.”

“That was rude to begin with,” Uraraka murmurs.

As Bakugou grumbles a reply, Denki can’t help but look back and forth between them. That’s… it? No interrogating, no protesting? He can’t read them like Hitoshi, but neither has ever been prone to lying to him.

Uraraka reaches for his hand, and squeezes it.

“I may be an asshole,” Bakugou adds lowly, as if the words are dragged out of him, “but I’m not fuckin’ blind. The fish is obviously good for you. So, stop anticipating our reactions and give us a little credit, dumbass.”

Something inside Denki that had knotted up in worry unravels in an instant.

He flushes with embarrassment and ducks his head, overwhelmed with fondness for the two people in front of him. They’ve been there every step of the way, as the weeks turned into months and the first brush with stuff of myth steadied into something palpable and undeniable and more real to Denki than anything he’s ever known. He chases his foolishness away with a stern thought and sheepishly rubs at the back of his neck.

“You’re right,” he laughs quietly. “I was being a dumbass, huh.”

Bakugou leans back, crossing his arms. “Damn right you were.”

Denki snorts; yeah, honesty as far as the eye could see. He picks up the discarded cast and tosses it aside, growing the collection of things he’s going to have no material need for, soon. A weird thought. “Good thing I have you to set the record straight, Bakugou.”

“Katsuki.”

For a moment, Denki freezes, then whips his head around and stares, meeting the heavy gaze of the other mechanic. “Uhm?”

Bakugou raises his chin, staring down the length of his nose in challenge. “My name, moron. It’s Katsuki.”

Denki flounders. “Well, yeah, I know that, I mean—”

“And you should call me Ochako,” Uraraka cuts in, leaning forward with a bubbly-light grin that leaves Denki flustered with its eagerness. “We did save a whole colony together, you know. That should count for something!”

It should. It does. And if not these friends, who else?

“Okay,” he agrees, voice shaky as he tries to belay the tears that threaten to blur over his vision. “Yeah, okay. Then call me Denki, yeah? I mean… the mer only use one name anyways, and it’s what Hitoshi knows me as, so. So I’ll be Denki. It’ll be good practice.”

Katsuki nods, his part in the discussion clearly over as he feigns interest in some of the nearby tools.

Ochako, though, beams. “Denki,” she says, as if trying it out, then: “Are you nervous?”

It takes only a beat for Denki to find the answer within himself.

“Actually,” he replies, eyes drifting closed. “I’ve never been more certain.”

The tides never stop moving. Not completely.

Change is good, refreshing, necessary, and the urge to use change has prickled inside Eri for as long as she can remember. Denki says it’s probably because she slept for so long—oh, he has no idea—but the why is so insignificant.

All Eri cares for now is the when.

Then, one night, she wakes up knowing. The tides rush to tell her, as if all the eagerness and relief and excitement that has been building in her pod has finally taken physical shape. It’s been hard to make sense of in the past moon, but now, the current’s path lays clear before her. Change is coming today.

She turns her eyes to the moon. This is going to be up to her, she knows. They’ve talked about it; she knows what she’s being asked, that she’s not losing any of her family but just shifting the shape of it slightly. They talk about it quietly and with soft encouragement and words, as if it’s something they think is difficult to understand, and more difficult yet to fix. Maybe it’s because they can’t feel the movement of Chaos the way she does. Maybe they don’t see that this ‘change’ they’re asking of her is easy, like untangling knotted kelp—simply straightening fronds that have always been twisted, waiting for her careful fingers. She’ll set them right, in a way they’ve never been before.

Right in a way they’ve always meant to be. The tides have told her so.

Eri reaches out through her bonds and touches each of the souls around the ship. Most are sleeping; few are awake. She can hear the tumbling brooks and rushing falls of their thoughts, recognize in turn the sharp angles of their worries and the rounded corners of their relief.

One, when she brushes him, brushes back. Eri? Hitoshi’s presence in her thoughts is like cool rain pattering the surface of the sea, gentle but steady. He’s somewhere beneath the boat, swimming lengths around it maybe, not even attempting to sleep. Is everything okay?

She pushes confirmation back at him with a short verbal trill that she cuts off when sosvii Aizawa shifts, curling his body more tightly around her. He barely fits in the little pool on the deck, and more than once has woken up grumbling about the arrangement, but repeatedly refuses to sleep in the colony grounds. This time though, he remains asleep.

Need something, or just can’t rest? Hitoshi presses.

It’s an open-ended question, which is something they’ve been working on—Eri knows all the words in Mermish and the walker languages, but she doesn’t think in them, not like the others do. When she offers her replies, they’re in pictures and colors and instinctual feelings first, and words second. It takes her a moment to find the right one to summarize her thoughts the best: Excited.

Oh yeah? His warmth and amusement tinge the thought; she can picture him smiling. What about?

She offers him a glimpse of the coming day, the Heart, the magic that’s thrumming in the waves as it readies itself for change. She doesn’t know how to translate so much into a handful of sounds for him. It’s so important to all of them, it’s what they’ve been waiting for. Excited. Excited!

Me too, Hitoshi replies faintly, desperately, and it’s like he’s left his heart right open for her to touch the strings. More than anything.

She pushes further into his mind, brushing across the golden-colored thought that’s pulling his attention. Golden hair, golden eyes. The fierceness with which Hitoshi holds that face close to his heart makes Eri smile.

Love, she thinks at him, giving it a name.

A very similar emotion branches out from him towards her at that, stretching in a gentle way until it wraps her thoughts in warmth. Yeah. Good. Yeah, it’s love.

She knew that already, though. Love is everywhere in her pod; they have enough of it between them to fill the whole ocean, she thinks. The colony, too, is using it to heal, to rebuild, to define themselves. It’s in their smiles and their hope, it’s their strength, their abundance. It’s the reason for their survival.

She pulls away from Hitoshi’s thoughts. Her eyelids droop and she buries her face into sosvii Aizawa’s chest. His arm settles around her, holding her close.

Love is something Eri knows she’ll never go without.

Which is good, because she has plenty of it to give back, too.

In a time before the sea meant more than him than the land, before he’d known the touch and taste of magic that wars were fought over and civilizations crumbled to protect, Denki had measured his successes in weeks and months and years. Time itself is a painfully humanizing restraint, when it comes down to it; there’s a desperate balancing act between too little and too late, because for all that their species is one of unstoppable progress and insuppressable innovation, one lifetime is surprisingly little to work with.

Just as with your flames, he recalls Toshinori saying once, You burn brilliantly, beautifully, brighter than anything else—and so terribly soon, you burn out.

A crucial design flaw in the human blueprint. Also one that might very well have been intentional, like a check-and-balance to regulate the aforementioned progress and innovation against the rest of the universe.

“You ready, kiddo?”

He knows he’s one of the lucky ones. The luckiest, even.

“…Kaminari?”

His measure of success had been skewed from the start. Now he sees the truth of it, in shimmering stones spread all through the dome-like ceiling of the Heart. Souls, all of them. Connected to one another, and to something that not even time can extinguish.

A hand jostles his shoulder, startling him. He blinks up at Yamada, who’s kneeling over him in the gleaming cavern with a punchy grin and laughing eyes.

“Can’t have you checking out on us now, little listener. The show’s about to start, and you’re centre stage.”

“Yeah, I—yeah,” Denki mumbles, heart doing backflips inside his ribcage. “I’m good! I’m good.” He shifts his back upon the warm stone, easing up on his elbows and craning his neck to glance around.

By virtue of the Heart simply being unable to accommodate the masses, they’d managed to keep the occasion away from the curious eyes of the rest of the colony. Everyone Denki can imagine wanting at his side for this is waiting in the water below, and that’s really all that matters, isn’t it? There’s Nemuri, holding a change of clothes and murmuring something to Aizawa with a sly grin as the latter makes his way to the raised rock with Eri in his arms. Nearby float Katsuki and Ochako, one silently studying various gems in the walls as the other gestures excitedly with her hands to different glittering groups of them. And closest of all, with eyes for nobody except Denki himself, is Hitoshi.

His mate’s lips curve into a small smile. Soon, he knows they’re both thinking.

Then Aizawa pulls himself up out of the water, his obsidian length dragging along the uneven rock as he moves to the opposite side of the raised platform from Denki. He sets Eri down between them, before raising his dark eyes to meet Denki’s gaze.

For a moment, Denki’s reminded of the last time they’d encountered each other here; those red irises had been equally as striking back then, but filled with threat, amnesia, violence. Not a hint of that nightmarish craze remains. Instead, he watches as Aizawa’s eyes gently half-lid.

The mer’s aurals relax, and he assumes a familiar half-smirk. “Let’s get this over with. I miss my bed.”

Denki nods rapidly, letting himself slide back down to lay flat on his back as Aizawa rotates to do the same.

“D’you… think I’m gonna look like you do?” he asks, unable to stop the nervous bubbling-up of all the questions he’d set aside and never gotten around to asking. “Like, black all over? Because it might not go with my hair. Unless that changes too—oh gods, I can’t even picture that. Me with black hair, I mean. I can tell sirens are usually dark, but… hold on, am I going to be a siren? Does your magic determine what subspecies of mer you are? I couldn’t find any concrete records of this kinda thing happening, but maybe if it has it just wasn’t documented—wait, do you think they would’ve kept records if it went wrong? Like that’d be a story passed down for sure, right? It’s just—”

“Kid,” Aizawa interrupts, voice low and soft, yet able to silence him in an instant. “Breathe. I don’t know those answers any more than you do, but it’s going to be alright.”

Denki swallows. His hands and feet prickle with the touch of anxiety he just can’t shake, but he does as instructed and takes a deep breath, shakily asking, “Yeah?” on the exhale.

“Yeah.”

Denki nods again, despite knowing Aizawa can’t see it from his own position. He bites his lip and continues the breathing exercises as Yamada slips off the rock to join the others, leaving just him, Aizawa, and Eri. While he should be focusing on what the blonde man is saying, all Denki can think of is, well shit, these are my last few seconds as a human, huh?

The idea of it stabs him in the chest, leaving him winded. The world spins even as he’s certain (mostly certain… somewhat certain??) that the rock beneath him hasn’t budged. Oh, fantastic, he’s going to throw up.

He jolts in surprise when Eri’s small, cool palm settles on his forehead.

“Wait—wait,” he gasps out under his breath, fingers scrambling at the stone on either side of him.

Another hand finds his, fingers intertwining and grounding him. “Denki?”

He can hear the worry in Hitoshi’s tone, feel it curling like a nervous creature in the empty space between them. Of course. Down here, where their connection thrives even without a full bond, Denki must be broadcasting every ounce of anxiety on a damn loudspeaker. He tilts his head and stares at his mate, immediately trying to form an apology for worrying him, insisting he wants this, he truly does—

“I know,” Hitoshi says out loud in response to the riptide of feelings that Denki can’t quite shove into words. The siren blinks slowly, drawing his thumb over the back of Denki’s knuckles. “Don’t worry. All safe.”

“Don’t let go,” Denki whispers.

Hitoshi’s gaze is steady as his aurals flare.

Whether it’s through Hitoshi’s bond or straight from the magic soaking every last atom of the chamber around them, Denki isn’t sure, but he feels Eri form an unspoken question at the forefront of his awareness: Ready now?

He squeezes Hitoshi’s fingers and closes his eyes. Will it hurt?

Eri’s mental giggle rolls through him like lapping waves and glimmering sunlight and parting clouds. The words aren’t as clear this time, but insinuation is unmistakable: she thinks he’s being silly. Warmth rolls through him from the point her touch instead of the cold Denki’d anticipated, relaxing his tension away almost as if on command. Feels nice. Feels right.

Peaceful.

It’s the last thought he has before he’s falling backwards through the stars, unbound from humanity.

.

.

He’s unmoored, afloat. The constellations behind his eyelids burn in colors he has no names for. He’s still sinking, somehow, but now there’s sensation to it. Hands push him down, down, down.

He does not care to resist. It’s possible that he couldn’t even if he tried.

He trusts those hands. He is content to drown.

.

.

.

At last, it’s dark and deep, but for once he doesn’t fear it.

Something strokes along the sides of his neck, brushing against what feel like twin slashes of open-ended nerves. A full-bodied twitch snaps through him at the sensation—discomfort, strangeness, unfamiliarity. He parts his lips to protest, but finds them quickly covered.

Voices hum and burble at the edges of his awareness. He strains to listen and is surprised to find new muscles that flex when he asks them to. The brush against his neck repeats itself, and he arches away from it, the muscles contracting and sucking water—

And it feels like a gasp of fresh air. The sensation licks through him pleasantly, and after a few moments’ consideration he does it again, forcing small currents through his body in this new, strange way. He focuses on that as someone moves to pull off his shirt—or the remaining scraps of it, how did that happen?—and gets the picture when the hands cause the same discomforting twitch at either side of his chest. Contract, draw in, expel. He teaches the new muscles in his torso this fancy trick. Breathing, but not.

He's—he’s happy. Not sure why, exactly, but everything is draped in this close, reassuring purple blanket of rightness, a promise that it’s going to be fine, you’re doing great, you’ve got this. He still feels impossibly heavy and unwieldy and different but it’s not unlike waking up in the dentist’s office with a numb mouth, or maybe waking up with pins and needles in his crossed arms after dozing off on the workbench for too long. Is that what this is? Waking up?

He can do that.

Denki opens his eyes.

Years from now, he’ll remember this blessing: that the first sight he gets to see in his new life is Hitoshi’s familiar, stunning face, wide-eyed and elated and glowing in so many hues of purple and pink that Denki can’t name them all. He wants to, he wants to chronicle every last detail of this moment, his vision sharper and more capable than it’s ever been, he thinks he’s even seeing new colors and he plans to treasure every single last one of them and—

And then Hitoshi’s features are front-lit by gold, and that doesn’t really make sense, until Denki realizes that the new light is coming from him.

Hitoshi’s surprise folds easily into the biggest grin Denki’s ever seen, and then he’s leaning forward in the water, pressing their heads together.

≈You are incredible,≈ he says raggedly. ≈Denki. Chaos, look at you.≈

The words drag Denki’s consciousness forward the rest of the way, and in an instant, he knows. He understands the near-automatic push and pull of water at his throat and ribcage to be gills. He understands the odd, disjointed flicking at his ears to be aurals. He understands why he can’t move his legs, because he has none, but when he shifts his hips and flexes his abdomen, a yellow-and-black mottled tail slides effortlessly through the water, knocking gently against Hitoshi’s own.

It's going to be an adjustment, that.

He’s thrilled.

Hitoshi’s hands cradle his cheeks, stroking across freckles of light and striped scales. His face slides up to nuzzle into Denki’s hair, then brush against—against horns, wow, yeah.

Denki wishes he could see himself. Maybe one of them up there has a mirror. Part of him wants to stay right here forever, where the world is lit up only by their care for one another – but they’re not done yet.

He can’t really speak Mermish yet and isn’t quite confident about talking without using his lungs, so he pulls Hitoshi’s forehead back down to his own.

Let’s go up, he says. We’re not done yet, yeah? It’s time. He smiles, giddy and bright.

Yes, Hitoshi agrees, closing his eyes. It’s time.

At the surface, he’s met with gasps and grins and beams back at them without hesitation.

His hands trailing along the canary-yellow of his tail, with its dusky gold and black patches in messy bands down the length of him. When Nemuri produces a mirror, he sees the same pattern across his face and upper body, how his bright irises now sit on dark sclerae and two horns like lightning bolts curve back over the crown of his head. His fins are sharp and sleek like a siren’s, and he still hasn’t stopped glowing from the freckle-like arrangements of bioluminescent scales scattered in winding patterns all across his form.

Denki meets the gazes of all of them, and commits to memory all of the details that his human eyes never picked up. The faces of all these people he loves, and whose love he can plainly see reflected at him in their eyes.

He finds Aizawa’s face last—human-shaped again, human for good—and his expression is the warmest of all.

“Looking good, kid,” the man murmurs, crossing one leg over the other and leaning against the wall, shoulder to shoulder with Yamada.

When Hitoshi lifts a hand back to Denki’s cheek, however, everything else falls away.

There’s no real ceremony when it comes to vows, Denki knows. Whether said privately or in the company of others, they’re binding all the same, a promise from soul to soul and to the Chaos from which all once came. Even the words aren’t technically necessary, for all the Denki insisted upon them the moment he’d heard of them from Yamada. But they’re beautiful, and symbolic, and—well, Hitoshi’s worth all of it.

They’ve been waiting so long for this, it’s easy to forget that they’re halfway there already.

He looks at the purple and yellow stones, embedded side-by-side in the chamber wall.

It feels so long ago now that they’d put them there, and part of him wonders if Hitoshi had known all along what such a thing might symbolize, what kind of oath he was making to the Heart when they gave those small pieces of themselves over. It had been the start of a bond, after all—the communication, the empathy, the promise to return. And here they were.

The currents had carried them together.

Hitoshi presses his forehead to Denki’s. I love you, he says simply, privately, just for them.

Denki feels like he could come to pieces with the wave of adoration that crashes over him.

Those are good words, wonderful words. I love you too, he thinks back. And yet they aren’t words he’s held onto quietly for weeks, the ones he’s practiced into perfection, the ones engraved in his heart for this exact moment.

So, on a shuddering breath, he lifts a hand to the back of Hitoshi’s neck.

The fin there feels like starlight and gentle rainfall and a quiet smile in the middle of the evening. It’s the magic that makes up Hitoshi himself, unique and unforgettable now that Denki’s soul has brushed along it and found its perfect match.

Hitoshi’s fingers trail across then settle on Denki’s own thoracic fin, and it takes his breath away. The magic in his own bones sings, bright and satisfied, and he knows this is it.

“Iri kiir de shavaar e asaeriik sho’alor irim syare daransuiir,” Denki whispers. Something inside him reaches, seeking, and finds its match in the words echoed back at him.

≈I see your soul, and within it drifts my chosen eternity.≈

Denki is home.

You've got a big heart
The way you see the world, it got you this far
You might have some bruises and a few of scars
But you know you're gonna be okay
And even though you're scared, you're stronger than you know
If you're lost out where the lights are blinding
Caught in all, the stars are hiding
That's when something wild calls you home
If you face the fear that keeps you frozen
Chase the sky into the ocean
That's when something wild calls you home

['Something Wild', Lindsay Stirling & Andrew McMahon]