Chapter Text
If there was one thing Casey was good at, it was getting into places and things he definitely shouldn't.
It was a nasty habit really, wiggling himself into all sorts of chaos and trouble over the years, landing in places as far between as a police holding cell and an alternate dimension. That being said, he usually wouldn't change a thing about it— the habit landed him friendship with the turtles, so any ill that came from it was easily outweighed by that one fact.
Usually being a key word in that statement.
Dashing through alleyways with a dislocated arm and what was definitely a concussion— trying to escape some incredibly fast, incredibly aggressive, brand new mutant— was one of the few times he’d say he wished he wasn't as good at getting into trouble as he was.
Now, the steps leading up to this sprint for his life were actually surprisingly simple; simple to the point where he really should have seen this coming.
It started, as most things where Casey finds himself in over his head do, with him noticing something while he was alone.
He had meant to simply do a light patrol of the area before tucking in for the night— the auto shop he worked at opened late enough, but working tired was Don’s thing, not his.
He’d been doing one last lap of the area around his apartment when he saw movement out of the corner of his eye, which drew his attention to the closed pharmacy that sat on the corner of the street. It was nearly unnoticeable really, the faintest flashes of something flitting past the windows, and at the time he’d mused that it reminded him of the turtles when they were only trying the bare minimum to sneak up on something.
He had approached, making his way over best he could while keeping an eye on the (then silent) store, and the closer he grew the more glimpses of the thing he got— a glint of something metallic, a definitely humanoid silhouette, the brightest color he could catch seeming some shade of purple and a slight blue glow.
Definitely not anything or anyone he recognized.
Then just as he was about to drop down from his place on the roof above, the thing slipped out a side door, quick , and so silent Casey was half convinced he was seeing things, managing to get himself moving just as it ducked around a corner.
Most other humans would have lost the shape within seconds, as it twisted and zipped away, barely stirring trash and making not a sound.
Most other humans also didn't have to keep up with master ninjas on a regular basis.
Not to say it was easy of course, the figure blended into the dreariness of New York shockingly well, and as Casey chased after it he was able to get a somewhat better glimpse of what he was dealing with.
With the slightly better look he could confirm it was humanoid, but not human. Its limbs and back were covered with something black, but the back part was notably a bit shinier (definitely metal), anything not black seemed some shade of dark green, and the purple he’d seen was from the strange rectangular markings around its eyes and its joints, the blue glow coming from what he could only assume was it's eyes.
And it was too damn fast to be human.
Everything else was idle observation— the faintly off shape of the body could just be his struggle to keep up making it hard to get a good look, the colors just clothes, but the speed? If Casey didn't have the advantage of going straight as the crow flies it would be long gone.
Its base speed was impressive enough, reminding Casey of sprinting dogs and horses, but on top of that it would occasionally get a sudden burst, practically blurring out of existence, and then appear a good dozen streets ahead of Casey.
Casey, who was steadily falling behind.
Even its split second pauses at some corners weren’t enough for Casey to keep a steady enough pace with it, and it’s with a stumble after his foothold crumbles that he starts to realize where exactly the thing is going.
The buildings near this particular dock were some of the oldest and most rotten Casey knew of that still stood. The old forgotten shipping yard had lost funding and was left to decay decades ago, and all that could be found here anymore were drunks and the occasional overconfident rat. Every building was one bad day away from falling to rubble, and the abandoned machinery wasn't much better. The entire area was just a breeding pit for rock jaw and rot.
Also incredibly hard to move around via rooftop.
Lucky for him, however, his target slowed, creeping through the area at a slow crawl compared to the breakneck pace it seemed to be rushing at earlier; this gave Casey enough time to scramble down from the roof of the warehouse he’d found himself on, drop down into the fog gathering below, and sneak his way forward.
Now that it wasn't blurred by speed, he was able to actually make out details.
Its back was covered by some black, almost shell-like metal mass; its limbs were wrapped in black cloth strips with the faint glint of metal buried in the left forearm; its hands and feet were separated into three distinct digits and its face was shaped strangely. Combine all that with the fact that it had dark green skin and Casey knew what he was dealing with.
Brand new mutant— nothing good came from that statement.
It was swinging its head from side to side, seeming to look for something as it let out soft, what Casey could only call… quacks? The sound reminded him of ducks calling for their ducklings. As it walked along he tried to follow as stealthily as he could, it hadn't noticed him yet and he'd quite like to keep it that way.
After a few seconds of his target making those noises, something answers.
The answering ‘quack’ is notably fainter, weaker even; it shakes and seems strained compared to his target’s calls. He'd even go so far as to call it smaller, once again reminded of a duck and its ducklings, and if it had a kid that overcomplicated things. Casey was a vigilante but he wasn't heartless, sure new mutants were normally a bad thing but there were always exceptions, if this new one was only causing trouble to take care of its kid who was he to do anything other than maybe help— hell knows he'd done and would do worse for his little sister.
He’ll tell the turtles and keep an eye out, but this wasn't something he needed to fight. They were all just trying to survive, after all, and he wasn't going to lower a mutant’s already low chances.
That’s his decision when he moves to leave, but he doesn’t manage to get even an inch away before the slightest of breezes picks up, blowing past him and straight to the mutant.
He freezes at the same time it does, its back straightening as it sniffs the air; it’s animalistic in its movements, like a wolf catching the scent of a wounded rabbit.
He can’t move as its head snaps in his direction.
The blue light from its eyes cuts through the fog to settle on him— a spotlight in the gloom revealing a hapless intruder— before yellowish-white eyelids snap over them. Those eyes seem to lock onto him no differently than a big cat that’d found its prey as another small quack from the other rings out; the call seems to hang in the air as time slows.
The one standing before Casey answers its kid with a hiss.
He never understood before, how snakes’ hisses could scare people or even spook other animals, but the noise the mutant lets out sends his heart racing. It’s not quick, it’s dragged out like a dog’s growl— a warning, a threat, a promise— it’s all of those things wrapped into one long low sound as its shoulders raise, body contorting in a way that pull its lips from its teeth, sharp fangs flashing in the moonlight like the axe of an executioner.
He can’t breathe when the metallic mass on its back seems to split open, spider like limbs reaching out, mechanical whirs and piston movement only adding to the auditory threat the hiss promises. The extra limbs seem to stretch, posing like a distorted multi-limbed deity, all turned towards Casey with one clear purpose.
Kill the intruder.
It takes a step forward and that manages to snap Casey out of playing dead, turning and scrambling to get away from what every remaining part of him screeches is certain death.
He manages exactly three steps when he feels something slam into his side, and he's abruptly reminded of the mutant's speed.
He crashes into the cold metal of a shipping container, vision going black as every part of his body screams. He’s not thinking when as soon as his body hits the ground he's scrambling to get up and away, heart pounding and chest heaving to try and regain oxygen as quickly as possible.
It’s still hissing, he can practically feel its breath on his neck as he runs. He can’t out-pace it, and there's no way in hell he can shake it in its own nest.
A flash of purple light has him diving to the ground on instinct— years of ducking out of the way of Kraang blasts saves his skull from being splattered against the concrete as he watches a sparking purple light breeze just past his face at breakneck speeds, in its wake a soft gust of air that rustles his hair as it goes past; his heart jumps into his mouth.
He already can’t feel his shoulder, his mind’s foggy in a way that he's long since memorized as concussed, and that was from just one hit .
He lands on his back and is already scrambling up and away, his only hope and goal being to get out of the mutant’s territory and pray it doesn't want to leave its young alone long enough to finish Casey off.
His lungs heave as he sprints past decrepit buildings and rusting machinery, heart skipping a beat every time the sound of metal clacking against pavement and that horrifying hiss grow closer. He’s not sure how far he can run like this, every inch of him aching yet not able to stop because stopping meant death.
So that’s how Casey ended up in this situation— running for his life from a pissed off mother mutant, arm definitely dislocated and without a doubt concussed, unsure if he was going to escape with his head still attached to his shoulders.
He does not stop to wonder why the noise starts to grow quiet, does not stop even when all he can hear is his own breathing and heartbeat, does not stop running until his legs give out beneath him and send him careening into the brick of an alleyway.
Only then does he stop and realize he made it, staring blearily behind him. Nothing — silence beyond the typical sounds of a New York night.
He collapses fully onto the ground when that silence sinks in, blinking confused as something in his pocket presses into his gut, weakly reaching out and pulling out…
A T-phone, the one Donnie gave him in case he ran into trouble… like, say, ‘a mutant determined to kill him’ kinds of trouble.
He groans, pressing the distress button before letting his forehead smack into the pavement below as the adrenaline dies down, too tired to even bother resisting the pleasant calling of a siren named unconsciousness.
—-
The sound of the distress signal going off was plenty enough for Donnie to find himself startled to the point of flinging himself out of his desk chair, scrambling up off the floor to stare at the blaring alarm that covered his T-phone’s screen.
If he wasn't in his lab he would have seen each of his siblings have a similarly startled response, the brief seconds of confusion crossing over their faces before there was a mad dash for the surface.
See, in those few seconds it took for each of them to realize what was happening, Donnie was able to assess a few things.
One, the signal was from Casey of all people, who had up until this point been more likely to lose his T-phone than ever actually use it.
Two, the area it was coming from was far outside the vigilante’s normal stomping grounds, miles away from even the furthest of Casey's sleepless nights.
Three, the most worrying… the signal wasn’t moving.
Now, to most that wouldn’t be that big of a deal, but as Donnie joined his brothers in racing across the rooftops he couldn't help but be reminded of the few times the signal didn't move. Either Casey had dropped the T-phone, making it almost completely useless, or he was trapped in some way unable to remove himself from the situation that apparently freaked him out enough to use it.
Both possibilities were far from ideal.
It took ten long, terrifying minutes of running and jumping across New York’s skyline before they finally managed to get close. Mikey, ever the fastest out of them, managed to peer down into the alleyway the signal was coming from first, his voice sending yet another pulse of panic through the group.
“Oh shell, he’s dead!”
…That had not been one of the possible scenarios Donnie had run through his mind.
Thoughtlessly Donnie finds himself practically throwing himself down into the alley, skidding to a stop in front of Casey's crumpled form.
Mikey's assessment was well founded. His normal mask has a chunk broken out of it to reveal a growing black eye, his left arm is at an odd angle, and Donnie can’t see him breathing.
He reaches forward, intent on finding a pulse, when Casey’s eyes snap open, right arm lashing out at him with a strangled yell.
It’s a weak hit, but the sudden movement is enough for Donnie to yelp, the sound drowned out by his brothers’ own exclamations of surprise. Casey’s eyes are feverish and bleary as he scrambles to his feet and away, left arm hanging limply in a way Donnie knows means it’s out of socket, leaving him once again to question what in the world happened .
“Dude what the hell, calm down it’s just us!” Raph barks out, which apparently works as intended as Casey’s eyes clear; they watch as his back hits the wall behind him and he allows himself to gracelessly slide down it.
There’s a few moments of silence as Donnie approaches again, hesitating only a moment before moving to check Casey’s arm, and he ignores the sharp yelp of pain as he tries to get a feel for how to put it back into place through Casey's thick hoodie. Nothing seems broken, but then again…
“What hurts, how’d you get hit?” he asks, wondering if he can convince the other to let him cut off the damn hoodie so he can do his job.
“Side feels like it’s on fire, head hurts a shit ton too, got wacked into a shipping container, I think…” comes Casey’s slurred response, causing Donnie to pause long enough to check his eyes, sighing in displeasure at the discovery that his pupils are two different sizes— concussion, of course.
“Casey what happened, start from the beginning.” It seems Donnie going into action snapped Leo out of his confused stupor, kneeling down in front of the vigilante as if it'll make a difference how close he is.
“Ok so, I was doing my patrol, right? And I like, I see someone in a closed medic shop or something, so I get closer and there's this like, mutant in there stealing stuff!” Casey pauses, seemingly in thought. “No idea what they even took come to think of it, they weren't really carrying anything, unless that back-pack-thingy doubled as an actual backpack?”
“Focus Casey, you said there was a mutant? Did you recognize them?” Leo redirects, Donnie taking the opportunity the interruption gave him to shove Casey’s shoulder back into place, wincing at the yelp Casey lets out.
“They were a turtle I think, but not like you guys, their shell was all metal-y and they were all lanky… and fast, really really really fast, god they were so fast…” Casey shivers then, starting to tilt to the side before Donnie makes him sit straight. “How the hell did they not catch me, they were so fast…”
“Considering your shoulder was out of socket I’d say they caught you,” Donnie mumbles, trying to cover up the sudden spike of fear at yet another new mutant running around, yet another enemy they had to learn the weak spots of.
“No, no if they caught me I’d be strips of jerky, probably being fed to the thing’s baby,” Casey hums, “this was the only hit they got in, some weird purple junk they conjured up, sent me into a container, metal shell thing had all these extra arms and junk, it wanted me dead. ”
“Its baby?” Mikey pipes up, eyes wide and in awe.
“Yeah, was followin’ it and I guess I got too close to its nest or somethin’, momma got real mad when it noticed me, it was doing this weird quacking noise and then there was this real little one that answered it, round then is when it noticed me and started hissing…” suddenly there's a look on Casey’s face, at least what can be seen from behind his mask. “…I’m not telling you guys where it is until you promise not to hurt her, just tryin’ to survive and junk.”
“Casey if they’re causing trouble—” Leo starts, only for Mikey to cut him off.
“Leo they've got a baby , and it was stealing from a medic place, meaning said baby is probably sick or hurt or something!” Mikey has his puppy dog eyes on, and Donnie notes how even Raph isn't saying anything, face scrunched up in a way of thinking. “It’s probably already hard enough being mutated, but to have a baby? A sick little baby and no proper place to take care of them?”
Unfortunately , Mikey has a point.
Donnie would probably be the first, if not the only person, to agree with Mikey on this point; this was unfortunately a lesser of two evils situation, and if a few pharmacys got robbed to keep a baby mutant from dying then he’d be willing to turn a blind eye. The question is just if Leo would be willing to do the same.
“We at least need to talk to them,” Leo ends up saying, voice a bit strained and eyes conflicted. “Maybe we can help, get them what they need without the chance of innocents getting caught in the crossfire.”
Donnie can’t help the sigh of relief that he lets out, standing from where he had finished checking Casey over.
“We should give them time to cool off, maybe wait until Casey’s healed to try and reach out? If we try right now they’ll still be agitated from someone getting too close to the baby,” he suggests, feeling himself relax when Leo nods in agreement, gesturing for Raph to help Donnie pick Casey up.
“Let’s get back to the lair, Casey can rest there for the night.”
Well, Donnie thinks to himself as he and Raph drag Casey to the nearest manhole cover, things just got a lot more complicated.
Another turtle mutant? It’s an odd thought, more of his and his brothers’ kind, and not only that but a turtle mutant with a hatchling . Were they like him and his brothers, or were they human turned mutant, a mix of both perhaps? With how the mother had apparently acted he wouldn't be surprised if they were turned humanoid instead of turned turtle. Humans turned seemed to keep their higher thinking levels, but from what he’d heard from Master Splinter— he resists the urge to flinch at the memory of his sensei— him and his brothers took a few months to click into a human way of thinking.
All something to think on when they get back home. he supposes, maybe if he can get the location out of Casey he can do some CCTV footage recon.
Maybe…