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Chapter Text

The house was too quiet.

Not the kind of quiet Zenitsu used to crave during those long stretches on the road—when Inosuke was shouting half-baked challenges at passing trees and Tanjiro was laughing at nothing, and Nezuko… Nezuko was watching them all with that curious tilt of her head, small hands folded neatly in her lap.

This wasn’t that kind of quiet. This was the kind that filled your ears like water. That muffled your thoughts until they rattled around and came back as something sharp and aching.

It had been weeks since the funeral, and still the air in the room clung to her—sweet, smoky, like sun-warmed cotton and old wood and something impossibly gentle. He’d stopped trying to clear it. Let it linger instead, like a ghost he didn’t dare banish.

Zenitsu sat cross-legged beside her futon, one hand resting on the edge like he was keeping vigil. He hadn’t made the bed. Couldn’t. The blanket was still rumpled the way it had been on the last night she lay there—burning with fever, chest rising in shallow fits. The doctors had thought it was aftershock from her transformation, something her body would recover from with time. She hadn’t.

He still remembered how her fingers curled slightly toward him as the light dimmed in her eyes. She hadn’t spoken, but her mouth had moved. His name, he thought. Or maybe her brother’s.

Either way, it was the last thing she gave him.

Tanjiro left the same day they buried her.

Didn’t yell. Didn’t cry. Just packed his things, hugged Zenitsu once—too tightly, too briefly—and whispered, “Thank you for loving her.”

That was it. No return address. Just one letter, weeks later. Three lines:

I need time. I’m sorry. Take care of each other.

Zenitsu had read it until the paper creased and tore in the folds. Until his fingers stained it with oil and sweat. Until the words stopped feeling like an apology and started feeling like a dismissal.

Take care of each other.

As if he and Inosuke even knew what the hell that meant.

Inosuke had been a storm since the day Zenitsu met him. Loud, brash, untamed. But lately—he was still wild, but quieter. Like he was holding something back. His grief didn’t spill out. It seethed. Tangled in muscle and instinct and silence.

They hadn’t really talked. Not since that night.

Zenitsu exhaled shakily and looked down at the tray in front of him. A half-eaten rice ball sat beside a bowl of miso soup—cold, congealed. He didn’t remember making it.

He barely ate anymore. Food sat heavy in his mouth. His stomach churned with every bite. But it wasn’t just grief that made him feel wrong.

Something had shifted in him.

His body was off. Achy. Overheated. His senses were too sharp, his skin too sensitive. He’d started waking in the night, panting, flushed, dizzy with need that didn’t feel like his own. His scent had changed too—he could smell it now. Richer. Sweeter. Unmistakably vulnerable.

He hadn’t smelled like this since he was a kid. Since he started hiding what he was.

Zenitsu closed his eyes and pressed a trembling hand to his chest. His pulse thudded too fast. He tried breathing through it—slow, deep, like Urokodaki had taught him. But even that felt hollow now.

He couldn’t let anyone find out. Not like this. Not when his world had already fallen apart.

He thought of Sanemi once—sharp-eyed and sharp-tongued, cruel in ways Zenitsu used to flinch from. But once, just once, after a mission gone wrong, he’d helped Zenitsu bind a wound with hands that were too gentle for someone so angry. They never talked about it.

He thought of Obanai and Mitsuri too—how they existed in this quiet orbit of each other, devoted in a way Zenitsu never truly understood until now. Until he lost what could’ve been his own.

And Tanjiro…

Gods, Tanjiro.

He was the kind of person people built their worlds around without realizing it. Zenitsu had fallen for him early—too early to make sense of it. A flutter in his chest that morphed into something brighter, sharper, deeper. But it was Nezuko he loved, too. Maybe more. Maybe differently. Maybe honestly.

He loved them both.

Now he had neither.

A sound broke the silence.

The creak of wood. A footstep. Then another—heavier, ungraceful. Familiar.

Zenitsu didn’t move. Just stared at the tray, the rice ball starting to split at the seam.

Inosuke’s footsteps stopped at the doorway behind him.

The silence shifted again—denser now. Less empty. Charged.

“You smell weird,” Inosuke said, voice flat and loud in the stillness. “Are you sick or something?”

Zenitsu flinched.

His breath caught in his throat. He turned just enough to see him—Inosuke standing there, sweat-dampened and wild-eyed, like he’d just come in from training or fighting or both. He was staring—not in anger, but with something like confusion. Something like instinct.

Zenitsu opened his mouth. Nothing came out.

He couldn’t lie. Couldn’t speak. Couldn’t breathe right.

For the first time in days, his heart jumped for a reason that wasn’t grief.

Inosuke stared a moment longer, then made a noise low in his throat—dismissive, maybe—and walked past him without another word, headed toward the back room where he sometimes slept, sometimes broke things.

Zenitsu stayed there, frozen, hand resting on the edge of a futon that didn’t belong to anyone anymore.

Something was changing. He could feel it.

He just didn’t know if he was ready.

Chapter Text

The letters were stacked in a neat pile by the window, each one sealed and addressed to a place Zenitsu no longer believed existed. He had been sending letters to places he knew Tanjiro could go in this state of mind.

He didn’t know why he kept writing them. Tanjiro wasn’t answering. He hadn’t since the first one—just after the funeral. Every week for the first 5 weeks, Zenitsu folded his heart into another envelope, walked it down to the post depot, and watched the courier nod like it mattered.

It didn’t matter.

He was doing it for himself, he knew. To keep himself from splintering. To pretend someone out there still wanted to hear from him. To pretend Tanjiro might still come back.

But pretending was getting harder. So, for the past several weeks, he stopped taking them to the post depot.

Zenitsu sat cross-legged on the floor, hands ink-stained, the paper in front of him blank.

The air in the house was warm and stale, carrying faint notes of sweat, rice, and old incense. The scent turned his stomach. Everything had started turning his stomach lately. The bitter tang of miso, the vinegar bite of pickled vegetables, even the pine-sweetness of fresh-washed clothes—it all hit too sharp, too fast.

He wiped his palms against his hakama, heartbeat rattling under his ribs. Another false start. Another letter he wouldn’t be able to send.

He kept drifting back to Nezuko—alive, human, warm in every way a person could be.

It had happened by accident, really. She had walked in one morning while he was changing—nothing dramatic, just bad timing. She saw him in profile, the towel slipping too low, the soft curve of something not expected.

He froze. Tried to speak. Couldn’t.

She didn’t scream. Didn’t look away in horror.

Instead, she stepped forward, wrapped the towel back around him gently, and cupped his cheek.

“You don’t have to explain,” she whispered. “But if you want to talk… I’ll listen. And I’ll never tell a soul.”

He did tell her. Not everything, not the biology or the blood cycles—but enough. Enough that she understood. Enough that she stayed.

She didn’t flinch. Didn’t treat him like he was fragile or strange. She just made him tea, kissed his temple, and braided his hair like it was the most normal thing in the world.

If anything, they grew closer. And for a while, it felt like enough.

He’d never felt more seen.

He’d barely had time to understand that feeling before it started slipping through his fingers. Her illness came quietly—fatigue, dizzy spells, a bruise that didn’t fade. At first, everyone thought it was just exhaustion. But her strength waned fast. Her limbs trembled. Her skin turned gray beneath the warmth. Her smile got smaller.

Tanjiro had unraveled right alongside her. Day by day, he dimmed—until the boy Zenitsu adored barely looked back at him anymore.

The weight of it sat thick in his chest.

Zenitsu exhaled shakily and reached for a fresh sheet of paper. He didn’t think. Just wrote.

—

Tanjiro,

You said we’d always be a team.

You said we’d protect her.

You said we’d stay together no matter what.

I’m not angry at you for leaving. I’m angry because you didn’t say goodbye. You left me with all this grief, and silence, and with him.

I don’t know what I’m doing. Inosuke doesn’t either. He keeps coming back like he’s waiting for something, but he won’t say what. Maybe he doesn’t know.

Everything’s wrong now.

I keep thinking about how soft her hands were. How she looked at you like you hung the moon. I wanted to tell her a hundred more things. I wanted you to tell me something—anything. But you didn’t.

And now I’m writing letters to someone who might not exist anymore. Are you even still the same person?

I’m not.

I miss you.

But maybe I miss the you I imagined more than the one who left.

If you ever read this—if you ever come back—I want you to know that I stayed. I stayed with her. I stayed for you. I stayed even when it hurt.

Please stay gone if you can’t look me in the eye anymore.

Please come back if there’s still a part of you that remembers me.

Either way, I deserve to know.

—Z

—

He stared at it for a long time after the ink dried.

The room creaked behind him.

Zenitsu didn’t look up.

“I thought you stopped writing those,” Inosuke said, voice too loud for the quiet house.

Zenitsu closed his eyes. “I didn’t.”

Inosuke crossed the room in three heavy steps. Zenitsu heard him stop near the window, probably glaring at the stack like it had personally offended him.

“Why do you keep writing if he’s not gonna read them? Do you even know where to send them? There was no address.”

Zenitsu didn’t answer.

He stared at the letter in his hands—this one thicker than the others, stained with ink and something heavier. He hadn’t sent the last ten. Hadn’t even dared. But this one…

This one mattered.

He folded it neatly and slipped it into an envelope.

Zenitsu stood up, turned, and met Inosuke’s gaze. His hair was wilder than usual, sweat matting it in loose, dark waves against his forehead. His jaw was tense. His chest rose and fell like he’d been running.

Zenitsu broke eye contact.

Inosuke didn’t push.

He just grunted and dropped to the floor in a heap of limbs, grabbing a rice ball from the tray without asking. He bit into it like it owed him money, then looked at Zenitsu again—eyes narrowing.

“You still smell weird.”

Zenitsu stiffened.

“I’m not sick,” he snapped, too quickly.

“Didn’t say you were.” Inosuke tilted his head, chewing slowly. “You’re just… different.”

Zenitsu swallowed the lump in his throat. “I’m tired. That’s all.”

“You don’t sleep.”

Zenitsu looked away again.

Inosuke didn’t press. He never did. But the silence between them now wasn’t just grief—it was something else. Something humming just beneath the surface.

Zenitsu could feel his body reacting to it.

He turned abruptly, wiping his left hand through his hair.

“I’m going to the post depot,” he muttered.

Inosuke didn’t stop him. Just watched him go, one sharp eye following the movement like he was waiting for something to break.

Chapter Text

Zenitsu had stopped trusting mirrors.

They never showed him what he needed to see. Just the blur of a face that barely looked like his own anymore—eyes ringed with exhaustion, cheeks flushed too easily, lips chapped from breathing too hard through half-suppressed panic, but plumper than usual. His hips starting to get curvier and harder to hide.

He adjusted the wrap across his chest for the third time that morning, hissing as it pinched too tightly near his ribs. The bindings were homemade—stitched from scraps of linen Urokodaki had taught him to layer just right—but even those old techniques were beginning to fail him.

His body was changing faster than it should.

By every account he’d scoured—every whispered scroll, every stolen book—this shouldn’t be happening yet. Not for another year. Maybe longer. And even then, the information was murky, contradictory, and dangerously vague. Rare Omegas were little more than rumor in most of the literature he’d found, especially ones like him. The ones born wrong. The ones that lived in hiding.

He tried not to think about the worst of it—the speculation that if the Demon Slayer Corps ever found out what he was, they’d mark him unfit for battle. Or worse. Sell him into an Alpha bloodline, hidden in some remote house to “carry legacy,” passed between elite slayers like a precious, pliant prize. At least, that’s what he read and was told by his grandfather.

He shuddered. No. He wouldn’t let that happen.

Urokodaki had sent him scent-masking patches in secret, hidden between layers of dried herbs and folded paper charms. No letter. Just a slip of handwriting that read: Stay still. Stay safe. Stay sharp.

Zenitsu wore one behind each ear now—thin, gray, and almost invisible beneath his hair. They burned slightly when he put them on, but the effect was worth it. The sharp edge of his scent dulled just enough. Not completely. But enough.

At least, he hoped so.

He slipped his haori on carefully, biting his lip as the cloth dragged across overstimulated skin. Every nerve felt like it was vibrating lately. Heat crept beneath his collar, unrelenting.

Outside, the wind shifted.

He froze.

A heartbeat later, Inosuke slammed the door open like it had personally offended him. Zenitsu nearly jumped out of his skin.

“Why are you up so early?” Inosuke asked, stepping into the room like he owned it. His boar mask was slung lazily against his hip, his blue-black hair tousled, extremely muscular chest glistening faintly from training. His round green eyes still looking wild as ever.

Zenitsu turned his back to him. “Didn’t sleep.”

“You never sleep.”

Zenitsu’s jaw tightened. “Don’t you have a tree to punch or something?”

Inosuke didn’t answer. Zenitsu could feel his stare—weighty and direct, like the tip of a blade just barely resting against skin.

“You smell like trees,” Inosuke said finally. “But not… really.”

Zenitsu’s breath caught.

“I bathed,” he lied, voice sharp. “Try it sometime.”

Inosuke just grunted and sat down heavily on the edge of the table, sniffing again like some kind of animal.

Zenitsu pretended not to notice.

—

That night, he dreamed.

He was sitting under the old persimmon tree behind the Kamado house, sunlight dancing across the grass. Nezuko was beside him, humming something low and lovely as she braided a ribbon through her hair.

He handed her a rice ball. Their fingers brushed. She laughed. He blushed.

“You don’t have to be nervous,” she said gently. “You’re cute when you blush.”

“You think I’m cute?!” he beamed.

She tilted her head back, smiling—then it turned into a full-on laugh. They both laughed hard at whatever hung in the air between them.

They didn’t kiss. Just sat quietly, hands folded together in the space between them.

And then—Tanjiro stepped out from the trees, basket in hand, smile tilted just slightly.

“I’m glad,” he said, voice soft. “You two make sense.”

Zenitsu’s heart had pounded even in the dream.

He remembered the heat of Nezuko’s fingers in his palm. The flicker of a moment where he thought: Maybe this is what peace feels like.

Two months later, she couldn’t stand without help.

—

Zenitsu woke with his legs tangled in sweat-damp sheets, his orange hair stuck to the side of his forehead and cheeks with his sweat.

His scent pressing hot against the corners of the room. His suppressants were failing. He felt wrong. Loose. Liquid. Tight in places he didn’t want to name.

He reached under his pillow, hands fumbling, and pulled out another patch. Peeled it. Pressed it to his neck.

It stung.

But the stinging was good. It gave him something solid to hold onto.

His door creaked.

Zenitsu sat bolt upright, heart in his throat.

Inosuke stood in the doorway, shirtless, one hand braced against the frame like he’d been standing there a while.

He was breathing too deep.

“You okay?” he asked.

Zenitsu’s voice was a scratch. “I’m fine.”

“You don’t look fine.”

“I said I’m—” He swallowed the growl in his throat. “—fine.”

Inosuke’s nostrils flared, but he didn’t step closer. Just stared, green eyes too bright in the dark, like something in him was flickering awake.

“You’re not like other slayers,” he said. “I know that.”

Zenitsu stiffened. “What’s that supposed to mean?”

“I’ve seen this before. In the mountains. Packs. Some wolves smelled different—like fruit or fire or—” he paused, sniffed again, “—like you.”

Zenitsu felt the floor tilt beneath him.

“They were protected,” Inosuke said. “The bigger wolves always circled them. I never understood why.”

Zenitsu’s throat closed.

“I’m not—” He looked away. “Don’t talk like that.”

“Like what?”

“Like you know anything.”

Inosuke tilted his head.

“I don’t know what you are,” he said plainly. “But I know I want to bite the air when you’re near me. That’s not normal.”

Zenitsu’s breath hitched.

“Go away.”

Inosuke stared another beat longer, then turned and walked off without a word, bare feet silent against the floor.

Zenitsu slumped back, chest heaving, the scent patches failing at the edges of his skin.

He was running out of time.

Chapter Text

They were only supposed to scout the area. That was the mission.

A minor demon, one survivor’s report, barely strong enough to draw two trained slayers. Zenitsu had insisted they take it—something simple, something small. Something to keep his mind off the way his skin had begun to burn beneath his clothes.

But something felt wrong. The bamboo was too still. No cicadas, no wind. Just the slow drag of his breath and the prickling weight of being watched.

Zenitsu swallowed hard. His fingers twitched at his sides, and a shiver crawled up the back of his neck despite the heat.

“Inosuke,” he whispered.

“What.”

“…Do you smell anything?”

Inosuke tilted his head. Sniffed the air like a wolf testing for snow. “Just trees. You.”

Zenitsu’s throat tightened. Exactly.

—

The sun had dropped behind the hills when they found it—or rather, when it found them.

Zenitsu heard it first: a breath too sharp in the wrong direction, the crackle of a branch behind thick bamboo. He turned just as it lunged—a blur of claws and fangs and wet breath, snarling as it slashed.

He dodged on instinct, barely avoiding the first swipe. Inosuke shouted something behind him, already moving, already unsheathing his blades.

The demon was fast. Not powerful, but vicious—darting from tree to tree with a hunter’s precision, forcing them into a rhythm they didn’t get to control. Zenitsu was quick. He always had been. But tonight, his vision wavered.

His chest felt tight. The scent patches were failing.

His sword connected once—cleanly—slicing across the demon’s ribs, exposing muscle and blackened bone. But as the creature shrieked and spun wildly knocking Zenitsu back, he stumbled.

He missed his footing on the slope.

The air left his lungs as he hit the ground—back crashing into a jagged tree root, side folding in on itself with a sickening crack. He felt a sharp stab in his side right after.

He gasped looking down at his now bleeding side —and the world swam.

A hot ache bloomed in his ribs, sharp and wrong, and something underneath his skin crackled. The scent patch behind his ear twitched at the edge of his jaw, burning faintly before fizzling out.

He tried to move—just a breath, just a shift—but the pain lanced so hard he nearly blacked out. His vision wobbled. The trees blurred together.

Not here, he thought. Not like this.

Then everything tilted.

—

Inosuke heard the break. It was so loud, he didn’t need to use beast breathing to hear it.

It was a sound he knew too well—the wet crunch of bone giving way. Something snapped in him right after.

He didn’t think.

Didn’t speak.

Didn’t even hear the demon’s next growl.

He charged, roaring as his twin blades carved a brutal X across the creature’s chest. He tackled the demon to the ground and stabbed both blades through its shoulders, then its throat, then its chest again—long after it stopped moving. Black blood coated his arms, his boots, his mouth. He didn’t care.

There was no elegance. No technique.

Only violence.

Only mine.

He didn’t stop after the demon stopped moving.

Even as it shriveled into ash, Inosuke kept swinging, kept slashing—until his chest heaved and his blades clanged against the rocks. Until the only sound was his own breath, ragged and wild.

Blood spattered his chest. His hands shook.

He looked down at the remains and saw nothing but red.

It touched him.

That was all he remembered thinking. Over and over.

It touched him.

He turned and sprinted back to where Zenitsu had fallen.

—

Zenitsu was on his side, curled tight, breath shallow. His haori was torn open along his ribs, the fabric damp with blood and sweat. Inosuke dropped beside him, panting.

“Oi,” he barked. “Don’t pass out.”

Zenitsu didn’t answer.

His chest rose once—barely. His skin was flushed all the way down his neck, and just below his collarbone, Inosuke saw it.

A patch of skin—glossy, swollen, warmer-looking than the rest. The scent was faint but wrong—not human, not demon, not like any wound he knew.

Something sweet. Wild. Calling.

Inosuke’s throat tightened.

It hit him like a buried memory—those winters in the mountains, the packs that roamed near the ravine. The way alphas circled their chosen, the way the air turned sharp when someone was close to blooming.

He didn’t know what it meant, not exactly.

But he knew this: Zenitsu was changing. And he hadn’t told anyone.

And it made Inosuke angry.

Not just at the secret. At the scent. At the danger. At the thing that had dared to touch him.

“Hey!” someone shouted behind him. Kanao, maybe—her voice always sounded too soft to be real.

Inosuke stood, blades still coated with demon blood, chest heaving.

Kanao approached from the clearing, sword unsheathed, eyes wide. “I felt your energy spike—what happened?”

She knelt beside Zenitsu without asking.

And Inosuke snapped. Something in him told him to protect his friend.

“Don’t touch him.”

Kanao froze. “What?”

“I said—” Inosuke stepped forward, low and growling, “don’t touch him.”

She stared at him, expression unreadable.

“Inosuke,” she said calmly. “He’s hurt.”

“I’ll take care of it.”

“You’re covered in blood. I have medical training.”

“I said, I’ll take care of him!”

For a moment, no one moved.

Then Kanao stood, backed away without another word.

Inosuke dropped to one knee, sliding an arm under Zenitsu’s knees and the other behind his back. He was careful—more careful than he’d ever been—with the way he lifted him. The cracked ribs were obvious now—layered over the wound from the tree.

The way Zenitsu hissed unconsciously at the shift. The way his body arched into the warmth like it knew what it needed.

Zenitsu made a soft, broken sound as he was lifted—like something in his body registered the contact before his mind could catch up. His arm curled weakly toward Inosuke’s chest, instinctive, half-conscious.

And Inosuke… held him like he was made of something holy. Not fragile, exactly—but important. His breath slowed just enough to anchor his grip. Every step he took away from the clearing felt heavier, more deliberate.

A part of him—the wild part—wanted to mark the space behind him. To warn anyone who might follow: mine.

Inosuke held him close.

“Stupid,” he muttered under his breath. “So stupid.”

But his voice softened. “I’ve got you.”

And he didn’t let anyone else near him for the rest of the night.

—

They made it back to the house just before dawn.

Inosuke kicked the door open with his heel, walked straight past the washroom, and laid Zenitsu down on the futon without loosening his grip until the very last second.

He washed his own hands at the basin. The blood wouldn’t come off.

He came back and sat beside him, cross-legged, alert.

Zenitsu’s face was pale but peaceful in sleep. His chest rose and fell slowly now—bandaged by Inosuke’s best effort. The heat had faded for the moment. The scent had dulled. But it was there.

And now Inosuke couldn’t forget it.

He reached out once, hovered his hand over Zenitsu’s cheek, then pulled back quickly like he’d almost touched fire.

“I don’t know what you are,” he whispered, “but you’re mine to protect.”

He didn’t know where the words came from.

He just knew he meant them.

He sat there for a long time after.

Not watching. Not waiting.

Just… staying.

Because somewhere deep in the animal part of him—the part that remembered claws and caves and den-building—he knew what it meant when your breath synced with someone else’s. When their pain made your chest ache. When their scent settled behind your teeth like hunger.

It meant: You don’t leave.

It meant: You stay.

—

Outside, the sky began to pale.

Inside, the room was still.

Zenitsu shifted once in his sleep, just barely—his brow twitching, fingers curling tighter in the blanket Inosuke had wrapped around him. His scent flared faintly, wild and unsteady, before settling again.

Inosuke didn’t move. Just watched.

The shift was coming. He didn’t know how he knew. He just… felt it. Low in his bones. Like the first tremor before the earth splits open.

Something was changing.

And when Zenitsu woke—he’d be different.

But Inosuke would still be there.

Chapter Text

Zenitsu woke with a sharp gasp, chest and side aching, limbs heavy. The world swam briefly—edges soft, air thick, something warm pressing against the inside of his ribs.

He blinked, trying to remember where he was.

The futon beneath him was familiar. The scent in the room less so. It was faintly pine, slightly singed—like wild earth just after lightning had struck.

And beneath that—something sweeter. His own scent, bleeding through the frayed edges of a failed suppressant patch.

Panic rose instantly.

He sat up too fast, groaned as pain lanced through his side, and shoved the blanket off. His haori had been removed, his chest wrapped again in linen—sloppy but secure. His fingers moved to check the heat gland just below his collarbone. Swollen. Visible. Too warm.

And freshly bandaged

He stopped breathing.

The door creaked.

Inosuke stood there, backlit by late afternoon light, arms crossed, one brow lifted.

“You’re awake.”

Zenitsu swallowed hard. “How long was I out?”

“Almost a day.”

He stepped inside, moving like he wasn’t entirely sure what to do with his limbs. Zenitsu watched him warily.

“I bandaged you,” Inosuke said casually. “You were leaking everywhere.”

Zenitsu flinched. “Leaking?”

“Your ribs. And your—” Inosuke made a vague circular gesture toward his chest. “The rest of it.”

A spike of heat slammed through Zenitsu’s stomach.

“You—” He pulled the blanket back up, heart pounding. “You saw?”

“I had to wash around and wrap them, dumbass. You were unconscious.”

Zenitsu turned away, face burning. “You shouldn’t have—!”

“What was I supposed to do? Let you bleed to death because you’ve got tiny hidden boobs?”

Zenitsu nearly choked. His scent flared—sharp, anxious, electric. The air shifted immediately.

Inosuke stilled and sniff softly.

His pupils dilated.

Zenitsu clutched the blanket tighter, curling in on himself

“Don’t,” he whispered. “Don’t smell me like that.”

“I’m not doing it on purpose.”

Zenitsu’s breath stuttered. “I can’t—I can’t let this happen—”

He turned to the wall, shaking, scent rising in waves despite himself. It wasn’t strong enough for a full bloom, but it was enough to stir everything around them.

Inosuke took a step forward—and stopped.

The scent hit him like a memory.

—

He was ten, maybe younger, crouched beneath a ridge of moss-covered stone. It was cold. Nightfall. He’d been tracking something when he heard it—a yelp, high and short. He crawled forward.

Two wolves in the clearing. One larger, sleek and silver. The other smaller, dark-coated, trembling.

The silver one bit the smaller one’s neck.

Not to kill.

Not to hurt.

And the scent that followed—

The small one released something soft and sweet, like crushed fruit on snow. The big one growled, and his scent changed too—spice, pine, and power. A claiming.

Inosuke hadn’t understood. Just stared until they curled together beneath the brush.

Later, the older wolves circled them. Protective. Respectful.

Mine, something had said. Ours.

He hadn’t thought about it in years.

But now—standing here, scent heavy between them, Zenitsu curled up and panting—

It clicked.

Not all the way. Not with words.

But with instinct.

—

“I’m not gonna touch you,” Inosuke said lowly. “I’m not gonna bite you.”

Zenitsu didn’t answer.

“I wanted to,” he added, bluntly. “Just for a second.”

“Why did you want to bite me?”

Inosuke shrugged, “dunno. You just smell really good.”

Zenitsu’s whole body trembled. 

Inosuke stepped closer. Sat down on the floor beside the futon, arms draped across his knees.

“I think you’re hiding something,” he said. “I don’t know what. But I’ve seen wolves that smell like you before.”

Zenitsu’s throat tightened

He wanted to deny it. Laugh it off. Scream. But his voice stuck to the roof of his mouth.

Because the truth was—he wanted to tell him.

Not just the technical truth, but the aching, exhausted truth of what it meant to be born wrong. To feel things he wasn’t supposed to. To ache in ways no one talked about. To be afraid of his own biology. To live in fear that one mistake—one wrong breath—could strip him of everything he’d fought to become.

He wanted to lean into that soft heat in Inosuke’s voice. Wanted to believe that someone as wild as him might understand. Might protect instead of destroy.

But secrets like his didn’t come with second chances.

So he said nothing.

“Don’t say that,” he murmured.

“Why not?”

“Because I can’t be one of them. I’m not—” He bit his lip, hard. “You don’t know what they’d do to someone like me if they found out. I won’t be in the Corps anymore.”

“Then I won’t tell them.”

Zenitsu looked at him, finally—wide-eyed, flushed, afraid.

Inosuke shrugged. “I don’t care what you are. You’re mine now.”

Zenitsu looked at him like he wasn’t sure whether to cry or punch him.

“You don’t get to say stuff like that,” he whispered. “Not when I can’t say anything back.”

“It still means something.”

“To you.”

“Yeah,” Inosuke said simply. “To me.”

They sat in silence for a long time.

Zenitsu’s scent slowly leveled out, no longer spiking with panic. Just warm. Sweet. Lingering.

Inosuke leaned back against the wall.

“You smell better when you’re calm,” he said. “So calm down.”

Zenitsu snorted softly. “You’re unbelievable.”

“Better than dead.”

Zenitsu nodded once. “Thanks. For… everything.”

Inosuke stood. “Don’t get mushy.”

“I’ll try.”

As he turned to leave, Zenitsu spoke again.

“Inosuke?”

“Yeah?”

“I’m not ready to tell you. But… thank you for not asking the wrong way.”

Inosuke didn’t reply.

But he didn’t leave either.

He sat down again—closer this time.

“I’m not going anywhere,” he muttered. “So, you better figure out what’s happening before you do something stupid again.”

A pause. Then, almost like an afterthought:

“Next time I’ll wrap your ribs better.”

Zenitsu flushed scarlet. He smiled faintly, even through the flush. “Next time,” he whispered, like a promise.

Chapter Text

Zenitsu had been hiding the heightening scent for weeks.

He told himself it was getting easier—not because it was true, but because the truth was unbearable. The patches burned when he peeled them off. His chest wraps strained as his breasts start to fill out. He woke sweating, breathless, aching in ways he didn’t have names for. But Inosuke hadn’t said anything—not about the scent, or the tension, or the way Zenitsu had started flinching from touch.

Maybe he didn’t notice. Maybe he was being kind. Or maybe…

Maybe Zenitsu just wanted to pretend a little longer.

They had gotten closer since the injury—still awkward, still circling, but not so fragile. Inosuke brought food now. Waited outside the bath. Sat on the edge of Zenitsu’s futon, muttering insults that somehow sounded like comfort.

And Zenitsu, traitorous body and all, found himself smiling again.

Then came the knock.

—

“I brought someone,” Sanemi said, already inside before either of them could say no. Giyuu followed silently, eyes scanning the house with his usual unreadable expression.

Inosuke’s jaw flexed as he stood between Zenitsu and the door.

“Didn’t think you two would be shacked up like this,” Sanemi muttered, tone easy but laced with something biting.

Zenitsu bristled. “We’re not—”

“Sure you’re not.”

Giyuu offered a respectful nod. “Just checking in. I heard about the injury.”

Zenitsu bowed stiffly. “I’m healing.”

“Good.” Giyuu’s tone was level. “You’re lucky.”

“We’re fine,” Inosuke added from behind Zenitsu—sharp, deliberate.

Tea was poured. The silence was heavy.

Sanemi watched him. From the first pour to the third sip. Zenitsu could feel the attention press against his skin, hot and too aware.

The itch started low in his neck.

He tried not to reach for it. Failed.

His fingers grazed the edge of his gland, wrapped and sore under bandages and scent patches.

And that was when Sanemi looked up.

Eyes sharpened.

Something in the air thickened—like the shift before a thunderclap.

“You alright, Agatsuma?” he asked like a dare,

Zenitsu shifted in his seat nervously.

Giyuu blinked once but said nothing.

“Mind if I borrow him for a moment?” Sanemi asked lightly. “Just want to ask a question. Privately.”

Zenitsu stood before anyone could respond.

Inosuke’s hand twitched at his side.

Zenitsu didn’t meet Inosuke’s eyes as he followed Sanemi down the corridor.

—

The walls felt closer than usual.

Zenitsu’s skin itched. His pulse thundered in his throat.

Sanemi waited until they were alone, then leaned in—just enough to trap him between the wall and something too large to escape.

His hands didn’t touch as they pushed against the wall. But they could have.

And Zenitsu knew it.

Sanemi’s voice dropped, quiet and cutting. “You don’t even know, do you?”

Zenitsu froze.

“K-know what, Wind Hashira.” Zenitsu shuddered.

Sanemi inhaled—sharp and deep. His eyes darkened.

 He was so close to Zenitsu’s fragrant gland.

Then he leaned closer, not touching, but enough to feel the heat coming off Zenitsu’s skin.

The lick across his neck was slow, almost reverent.

Zenitsu gasped, knees buckling. His scent spiked.

“You’ve been hiding it so well,” Sanemi murmured. “But it’s becoming harder now. Isn’t it?”

Zenitsu tried to step back. His body didn’t listen.

“I thought I smelled something… months ago when I helped you during training. Barely there. Almost missed it.” Sanemi’s voice was low, intimate. “But I never forget a scent like that.”

Zenitsu swallowed hard.

“You’re rare,” Sanemi said. “Precious. And I know exactly what you are.”

Zenitsu stopped breathing. This pleased the Hashira.

“I’ll make you a deal,” Sanemi said almost like a threat. “You let me mark you. Not now—next year, even months with how strong your scent is, you’re almost ready. But we must wait until you’ve fully bloomed and ripe.”

His breath brushed Zenitsu’s cheek.

“And in return, I’ll tell you everything. About your kind. About what you need. About what comes next.”

Zenitsu’s heartbeat stuttered.

Sanemi leaned in, mouth near his temple. “But to seal it, you’ll let me be your first. Let me take you. Now. Before anyone else gets the chance.”

Zenitsu blinked—mind spiraling, thighs clenching, shame and heat colliding.

“You’ll carry my scent. Live under my roof. Take my name.” Sanemi’s tone dropped to a whisper. “I’ll protect you. Keep you safe. No one else will touch you.”

He touched Zenitsu’s cheek—fingers calloused and still but calming.

Zenitsu opened his mouth to speak, but he leaned into the touch mindlessly.

He closed his eyes and as he was about to agree, Inosuke’s beautiful eyes flashed quickly in front of him. He quickly opened his eyes and stepped back.

“I-I can’t do that. I want to know more about who—what I am, but I can’t give myself to you. It’s too dangerous and…” Zenitsu felt fear creep up his neck, but arousal shamelessly lingered too. He was burning up and the place below his belly was getting wet,

Sanemi must have smelt the wetness; he sniffed the air deeper and growled. He looked liked he was trying to mask his anger and lust, but it was all in his eyes and scent.

Zenitsu backed up as far as he could from the Hashira, which wasn’t too far. He was cornered,

The smile that curved Sanemi’s lips was slow, cold, promising wrapped around a threat. It was sickly sweet to the point that Zenitsu could smell it wafted the air around him.

Sanemi began stepping closer to the orange haired omega, but then the sound of swords being unsheathed stopped him in his tracks.

They both turned at the same time.

And Inosuke was there—halfway down the hall, eyes locked on Sanemi, blades drawn. Standing in a fighting stance, ready to lunge.

He hadn’t moved silently.

He hadn’t tried to hide.

The tension was unmistakable.

Inosuke’s grip on the hilt tightened.

Sanemi’s gaze sharpened adjusting himself so he’s facing the boar head maniac.

They didn’t speak.

Didn’t need to.

For what felt like hours, the corridor vibrated with something dangerous—unspoken, scent-charged, Alpha-heavy.

Sanemi bared his teeth, now recognizing the scent he’s smelling from Inosuke.

Before either could charge, Giyuu stepped into view.

“What’s going on? I felt some weird energy spikes.”

His voice broke the stillness. His eyes scanned the hallway, Zenitsu’s flushed face, Sanemi’s venomous smile that only seemed like anger, Inosuke’s stance ready to go for the kill.

He didn’t speak further.

Didn’t ask.

Just stepped in between the two Alphas.

Sanemi’s eyes didn’t leave Inosuke’s.

Then he turned back to Zenitsu—his expression smooth, indifferent.

“I’m not done. You’ll see me again,” he said softly but with a bite.

Then walked past Giyuu like nothing had happened.

Giyuu hesitated a beat. Glanced at Zenitsu puzzled at his face.

Then, without another word, followed Sanemi out.

—

The door closed.

Zenitsu let out a sound—half gasp, half sob—and slid down the wall, shaking.

Inosuke ran to him.

“Monit-Zenitsu?!”

He didn’t speak.

Inosuke dropped to his knees, catching him before he crumpled completely.

Zenitsu trembled in his arms, eyes wide, glassy. “It—it hurts,” he whispered. “I need—”

He rubbed against Inosuke’s leg, breath ragged. “Please—just touch me—I can’t—”

Inosuke froze.

Zenitsu clung to him, moaning softly, grinding closer like his body didn’t care what his mind said.

And for a moment—just a moment—Inosuke didn’t resist.

He kissed him.

Zenitsu melted into it, arms wrapping around his neck, mouth open and warm. He pressed his chest against Inosuke’s, crying softly, lips trembling.

“I thought—I thought I could wait—I didn’t want—” His words blurred into moans. “He said—he said he knew what I was—he said he’d protect me—”

“Did you want him to?” Inosuke growled, sharper than intended.

Zenitsu sobbed harder in between kisses. “Yes, no—I almost did—I didn’t even say no fully—I just thought of something and pulled away—I didn’t want to be tied to him—I didn’t want it to be anyone else but—” Zenitsu stopping himself.

Inosuke’s breath caught like he knew what the unspoken words were.

His whole chest tightened.

He never thought he could get this close to Zenitsu. All those nights after Nezuko, wishing he could kiss Zenitsu to make it better. He had pushed those thoughts out of his head long ago, so he thought. Didn’t know what was going on with him now. His mind couldn’t focus on this kiss like he wants. He knew it was wrong to do this when Zenitsu was like this, even if he doesn’t understand what this is. He kept thinking about why he was so angry that Sanemi was so close to Zen… he could smell what Sanemi was thinking. He wanted to rip his fucking throat out, but why? He wanted to claim Zen right now, whatever that meant.

He pulled back from the kiss, panting. Zenitsu looked up at him—flushed, sweat-slick, beautiful. Inosuke wanted to keep kissing him so bad. His lips tasted sweeter than any sweet he’s had. His body was soft and smelled like heaven.

“Don’t stop—please—”

“I—” Inosuke stared at him. “I don’t know what to do.”

Zenitsu tried to strip his clothes off. Inosuke stopped him with both hands, trembling.

“Wait.”

Zenitsu whimpered. “Why? Why not—”

Inosuke lifted him—gently, without a word—and carried him to bed.

Zenitsu didn’t fight. Just cried, body too hot, scent too thick to hide.

He shed the last of his clothes, bare under the thin sheet Inosuke laid over him.

“I think—” he gasped, “I think it’s my first heat—”

Inosuke said nothing.

Every breath Zenitsu took spiked the air again—ripe with need, shame, and longing.

Inosuke sat beside him, trying not to breathe too deep. He knew he was on the edge himself, but he couldn’t bring himself to give in.

His whole body thrummed with heat. His hands wanted to grab. His mouth wanted to bite. His cock twitched more than it ever had before. He has only self satisfied, but his mind usually drifted to images of Zenitsu’s golden brown eyes looking up at him when he was finishing. He dreamed about those eyes even when he wasn’t pleasing himself.

Zenitsu’s tears hit hard, and he could feel his sadness. He couldn’t do that to him tonight.

Inosuke leaned down and pulled him close.

“I don’t know what I’m doing,” he whispered. “But I know I’m not letting anyone else touch you. Not like that. Not ever again. Especially a man like the Wind Hashira.”

Zenitsu broke.

Tears spilled faster. “Then stay. Please.”

Inosuke held him tighter.

Zenitsu buried his face in Inosuke’s chest and wept.

And Inosuke—feral, confused, trembling—said nothing.

But in his heart, the vow had already formed:

I’ll learn. I’ll figure it out. I have to. For him.

Chapter Text

The light through the slatted window was too soft to be morning, too gray to be comforting.

Zenitsu lay still under the sheet, eyes half-closed, heart drumming unevenly in his chest. The fever had broken sometime in the night, leaving him wrung out and aching—not just between his legs, but everywhere. His throat burned. His hips felt tender. His scent clung thick and bitter to the room, even under layers of old incense and cedarwood.

He’d cried himself to sleep in Inosuke’s arms.

And now he didn’t know how to look at him.

He could hear Inosuke moving around in the next room—heavy-footed, muttering to himself. The sound was grounding, oddly soothing. But it didn’t help the heat blooming again low in his belly or the sharp edge of shame that came with it.

Zenitsu turned his face into the pillow and tried to disappear.

A knock—soft, for once—at the door.

He didn’t answer.

It opened anyway.

Inosuke stepped in, bare-chested, still damp from washing. His hair was pulled half back with a bit of twine. His features so soft for someone that’s so wild and untamed. He carried a bowl and a rag, frowning like he’d stolen them from somewhere and wasn’t sure why.

“You still smell weird,” he said bluntly, padding over.

Zenitsu flinched. “Don’t—don’t say that. I already feel disgusting.”

Inosuke tilted his head. “That’s not what I meant.”

He set the bowl down and knelt beside the bed. “You smell like you. Just… more.”

Zenitsu’s eyes welled again.

Inosuke reached forward—awkward, careful—and pressed the cool rag to Zenitsu’s neck. “You’re not gross. You’re… different. But not bad.”

A pause.

Zenitsu looked away, whispering, “He said I was rare.”

Inosuke’s hands stilled.

Zenitsu swallowed hard. “Hashira Sanemi. He said—he said I didn’t even know what I was. That I was… precious. But only if I gave myself to him.”

He clenched the sheet, fingers trembling. “I almost did. I almost let him. It was like I couldn’t think, couldn’t breathe… and he—he licked me.”

Inosuke growled under his breath. The sound was deep, guttural, barely restrained.

“But I thought of you,” Zenitsu whispered. “That’s what stopped me.”

Inosuke froze.

Zenitsu sniffled. “You were out there. Watching. I felt it. And I—I didn’t want anyone else to be the first. Even if you hate me after this. Even if you never want to touch me. I just… I didn’t want it to be him.”

Inosuke’s eyes widened, then softened. “I don’t hate you.”

Zenitsu blinked.

Inosuke leaned back, resting on his heels. “I don’t know what any of this means. But I know what I saw. I saw him corner you. I saw you scared. And I wanted to kill him.”

His voice dropped lower, unfamiliar. “I never wanted to protect anything before.”

Zenitsu’s breath hitched.

“I remembered something,” Inosuke said, voice far away. “When I was little. I saw this wolf get bit—by one bigger than him. Right here.” He tapped his neck. “The little one gave off this smell… like pain and happiness. It was a little sweet like your smell. The big one smelled like mine.”

Zenitsu’s lips parted, stunned.

“I didn’t get it then,” Inosuke admitted. “But when he touched you… and you looked at me after…”

He trailed off, eyes dropping to Zenitsu’s collarbone.

“I think I’m starting to understand.”

Silence filled the room.

Zenitsu sat up slowly, sheet pooling at his waist no longer hyperaware of his naked body. “You’re not scared?”

“No.” Inosuke’s voice was firm. “But I’m mad. I don’t know what’s happening to you—or to me. But I’m gonna find out.”

Zenitsu nodded slowly, biting his lip.

Inosuke looked at the marks still faint on Zenitsu’s neck—the ghost of Sanemi’s intrusion. He clenched his fists.

“I should’ve stopped him sooner.”

“You did,” Zenitsu said softly. “You did.”

Inosuke hesitated, then leaned forward. His hands cupped Zenitsu’s face like he was learning how to be gentle.

“You’re not weak,” he whispered.

Zenitsu’s chest cracked open.

Tears slid down his cheeks—quiet, uncontrollable.

Inosuke let them fall. He pressed their foreheads together, not moving, not speaking. Just staying.

—

Elsewhere

Sanemi stood on a rooftop, staring down at the distant road leading out of town. His jaw flexed. His fingers twitched.

The scent was real.

He was sure of it now.

And the moment that little fox slipped too far from his unknowing Alpha?

He’d be waiting.

Chapter Text

Zenitsu thought pretending things were back to normal would be easier than this.

The house was quiet. The scent markers had faded. His fever was gone. Inosuke even stopped watching him sleep like some wild-eyed sentry. And yet… every time Zenitsu turned around, Inosuke was there.

Not looming. Not aggressive. Just close.

Too close.

He hovered near doorways, tracked their surroundings like prey was waiting in every bush, and—most notably—positioned himself between Zenitsu and everyone.

He couldn’t brush his teeth without Inosuke hovering in the hallway like a hulking ghost. Couldn’t train in the yard without hearing the unmistakable huff of a watching boar. Couldn’t even take a piss without the distant clang of someone sharpening swords—loudly, as if to say “I’m close. Try something.”

It was exhausting.

It was infuriating.

It was endearing.

It was confusing as hell.

“I don’t need a babysitter,” Zenitsu muttered one morning, yanking his sleeve straight. “You know that, right?”

Inosuke just blinked.

Zenitsu glared. “Seriously. You don’t have to track me everywhere I go like some—some lost dog.”

Inosuke’s brow furrowed. “I’m not lost.”

“That’s not the point—!”

“Would you just stop following me around like a bodyguard, please?” Zenitsu snapped, adjusting his uniform collar. “You’re not my mother.”

Inosuke blinked. “Dunno what a mother is.”

Zenitsu groaned, pressing his palm to his face. “Just—give me space.”

Inosuke grunted but didn’t move. “You still smell different.”

“I’m not sick. I’m trying to hide it better. It’s just not working so great.”

“I didn’t say you were.” Inosuke leaned in, eyes narrowing. “But I know how animals guard their mates.”

Zenitsu flushed instantly. “We are not—!”

“Didn’t say that either,” Inosuke shrugged, smirking slightly.

Zenitsu sputtered. “Wh—what does my smell have to do with anything anyway?!”

Inosuke squinted. “Weird things follow weird smells.”

Zenitsu stared at him.

Then sighed. “I hate how that makes sense.”

Zenitsu didn’t know whether to punch him or pass out.

—

They were dispatched two days later—a small village north of the last cluster of demon sightings. Zenitsu was cleared for active duty again, and though the sting of lingering aches and unasked questions hadn’t left, he welcomed the distraction.

Kanao and Mitsuri joined them, which should’ve been a relief.

Instead, Zenitsu felt more exposed than ever.

He noticed it first when Mitsuri greeted them.

“Zenitsu! Inosuke!” she chirped, arms full of sakura-wrapped onigiri. “I brought snacks! You’ve both been so quiet lately, I figured I’d tag along.”

“Tag along?” Inosuke muttered. “Aren’t you a Hashira?”

“Hashira get bored too, y’know,” she winked.

Mitsuri lit up as she shoved the treats in their mouths. “You look so cute traveling together!”

Inosuke puffed out his chest. Zenitsu blanched.

“We are not traveling together,” he hissed.

“You literally slept on his shoulder,” Mitsuri said cheerfully, pointing to a smear of yellow on Inosuke’s haori. “Still shedding, huh?”

Zenitsu covered his face. “I hate my life.”

Kanao said nothing but nodded slightly to both of them, her eyes scanning Zenitsu in that unreadable way of hers.

Zenitsu clutched his sword tighter.

The mission itself was quick—a pack of low-ranking demons terrorizing the outskirts of a spring market at night. Zenitsu had moved fast—faster than he used to. Awake. Alert. His strikes were sharper, surges of thunder dancing off his blade like it belonged to him now, not some former version of himself. He’d unlocked two new techniques in the last few weeks, and he wasn’t afraid to use them.

He felt powerful.

And for the first time in a long time, worthy and capable.

But it didn’t stop Inosuke from flinging himself in front of every danger like a one-man wall.

Kanao noticed first, head tilting mid-swing.

Mitsuri noticed next, smiling like it didn’t surprise her at all.

“I had that one!” Zenitsu barked after Inosuke shoulder-checked a demon so hard it hit a tree.

“You were too slow.”

“I was charging—!”

“Still slow.”

Zenitsu stomped away in frustration while Mitsuri and Kanao exchanged a look. Kanao arched an eyebrow. Mitsuri just beamed knowingly.

After the demons were dead, and the cleanup began, Zenitsu retreated to a small stream nearby to rinse blood off his arms. Mitsuri followed without a word, crouching beside him, pink and green braid swinging gently over her shoulder glowing in the moonlight.

“You were amazing today,” she said softly.

Zenitsu stared into the water. “Thanks.”

“I mean it. I’ve never seen you so steady.”

He stayed quiet. The wind tugged gently at his golden hair.

Mitsuri’s tone gentled. “I know you’ve been through something. I won’t ask what. But… Tanjiro’s absence hurts all of us. Especially you.”

Zenitsu blinked hard. “He’s been gone five months.”

“I know.”

They sat in silence for a moment.

Then Mitsuri smiled again—soft, warm, maternal.

“You’ve gotten stronger.”

Zenitsu glanced at her. “I had to.”

Mitsuri’s eyes flickered with understanding. “You miss her.”

Zenitsu froze.

“She meant a lot to you,” she added. “They both did.”

Zenitsu didn’t speak for a long time. The water shimmered around his fingers.

Mitsuri folded her hands in her lap. “You don’t have to explain. Loss makes us all strange for a while. Angry. Quiet. Different.”

Zenitsu’s throat tightened.

“But I’m glad you’re still here,” she said. “And not just surviving. Living. Fighting. Making people smile—even if you pretend you’re not.”

He blinked hard, fighting the urge to cry.

She nudged him gently with her shoulder. “You’ve got that silly guard dog now, too.”

Zenitsu huffed a small laugh. “He’s not my—”

“Please. He circles you like a wolf who’s imprinted on his favorite rabbit.”

Zenitsu flushed to his ears. “I hate how that makes sense.”

Mitsuri giggled. “He’s not subtle. But he’s loyal. And maybe that’s what you need right now.”

Zenitsu glanced back toward the treeline, where he could just make out Inosuke’s silhouette pacing the perimeter.

“Maybe,” he whispered.

Mitsuri stood, brushing cherry blossom petals from her knees. “My home is open to you. Anytime. For rest. For tea. For hiding from overgrown wild boys with boundary issues.”

Zenitsu laughed what felt like the first time since his world was shattered.

Then Mitsuri leaned down, ruffled his hair like a little brother.

“And tell Inosuke he’s not as sneaky as he thinks.”

Zenitsu turned to watch her walk away—gentle, radiant, powerful.

He felt something settle in his chest for the first time in weeks.