Archive of Our Own ^beta

Chapter Text

The rain starts halfway through the chase.

Raph's boots slam against soaked concrete as he vaults across a narrow alleyway. Neon lights flicker in puddles below – distorted, broken. Just like the thugs he's hunting.

“C’mon, you idiots,” he growls, sliding into a crouch on the next rooftop. “You gonna make me chase you all night?”

The trio scurrying ahead finally stops running. One drops a crowbar with a heavy clang and pulls a switchblade. Another’s got a length of chain, the third grips a pipe. They're cornered, but still cocky.

"You shoulda stayed in the shadows, freak," one spits. "This ain’t your turf."

Raph's sai twirls into his hands, catching what little light the city offers. He doesn’t speak. Just breathes – deep and heavy – more than he should be after a chase this short.

Lightning flashes.

The fight starts.

The first guy lunges, chain whipping out, but Raph ducks, rolls low, and slams a boot into his ribs. The impact hurts . Not just for the guy but for Raph, too. Pain shoots down his side like someone jammed a screwdriver into his ribcage. He snarls and pushes through it.

Second guy swings the pipe. Raph blocks it with his sai, then counters with a brutal elbow. His movements are still fast, but not fluid. There’s a slight delay in his reaction – just a hair slower than he used to be.

He notices, just barely. Blames the rain.

Then the third guy gets behind him. He hears the crunch of boots a split-second too late – turns, raises his arms, but the stun baton hits his shoulder with a crack-zap! and he drops to one knee, muscles seizing.

His breath comes sharp and shallow.

He’s panting .

Raph slashes out blindly, catches someone’s leg, and rolls to the side. He springs up, but it takes longer than usual. Too long. His left leg trembles under him. Weak. Like it might give. He fights like a damn demon anyway.

It’s messy. He wins, but not without taking more hits than he usually would. His knuckles are bleeding. His head spins. And by the end, he’s standing over the last thug, staring down, chest heaving in hard, uneven gasps.

He grips the side of the building to stay upright.

The rain hides the shaking.

“Tired,” he tells himself again, more forcefully this time. Didn’t stretch. Haven’t been eating right. Just need a real night off. Maybe a vitamin or something. Nothin’ serious.

He spits blood. Doesn’t notice that he misses the edge of the rooftop by a good six inches when he tries to hop the next ledge home. He slams into the bricks, scrapes his side, but grits his teeth and claws over it like it’s nothing.

The pain lingers longer than it should.

~~~

The lair is quiet when he slips in, too quiet. The kind of stillness that makes old metal hum louder than it should and every leaky pipe sound like footsteps.

Raph keeps to the shadows anyway, out of habit. He peels the Nightwatcher helmet off slowly, wincing as it scrapes the fresh bruise blooming along his jaw. His fingers fumble the latch more than once. They feel stiff, clumsy, like they don’t belong to him tonight.

He doesn’t bother cleaning the dried blood on his arm. Just peels off his gear piece by piece, drops it by the door in a trail to his room like breadcrumbs. Everything aches. His shoulder throbs from the stun baton. His ribs feel tight when he breathes too deep. The room swims a little when he stands still too long.

You’re fine. Just tired. Just a bad night.

He mutters it like a prayer. He believes it like a lie.

He gets to his room. Collapses onto his bed. The springs squeal under him. He doesn’t even pull the sheets over himself. Just lies there, face half-buried in the pillow, letting the cold from the sewer stone floor seep in.

He tries to sleep.

He doesn’t.

Minutes crawl into hours. The only light in the room is from the old clock on his wall, the faint green glow flickering just enough to keep his eyelids twitching.

He stares at the ceiling.

He still can’t breathe right

~~~

Eventually, the ache in his chest gives way to something else – hunger, or maybe thirst. Or maybe he just needs to move. Get up. Pretend this is normal. Pretend the night didn’t feel like it took something out of him he won’t get back.

So he drags himself up, legs shaky, and makes his way toward the kitchen.

The kitchen was dim, cast in that hazy blue tint that came with the early hours of morning. Raph squinted as the light flared too brightly in the otherwise shadowed lair. He winced, quietly cursing himself for not grabbing his hoodie, his entire being felt too bare under the chill.

He barely noticed the second figure until he heard the quiet clink of ceramic on ceramic.

Donnie sat at the small kitchen table, curled around a mug of something that smelled bitter and herbal. Maybe tea. Most likely that strong coffee he liked to drink on all-nighters. Whatever it was, the mug was almost as oversized as the bags under Don’s eyes.

Raph blinked. “Didn’t expect you to be up.”

Donnie looked up, lips quirking into a tired smirk. “Didn’t expect you to be either. Thought you were on a lazy streak.”

It was a gentle jab. Nothing unusual.

Raph gave him the smallest ghost of a chuckle – barely audible, really – and moved past him toward the cabinet, grabbing a glass.

“Couldn’t sleep,” he said gruffly.

He filled the cup slowly, deliberately, watching the water swirl like maybe it held answers in it. His muscles ached. His ribs still twinged when he breathed in too deeply. But that wasn’t the problem. Not really.

He was just… so tired.

Not the kind of tired you could nap away. Not even the kind you fixed with a week off or one of Mikey’s stupid homemade smoothies. This was bone-deep. Permanent-feeling. Like he was dragging his whole body behind him every time he took a step.

And lately? Even the wins didn’t feel like wins anymore.

“You okay?” Donnie’s voice was softer now, the teasing gone. That scientist’s intuition prickling like it always did.

Raph hesitated. Just long enough to make it weird.

“M’fine,” he said. “Just tired.”

He didn’t turn around. Didn’t look at Donnie’s face. Just took a sip from the glass, even though the cool water felt wrong in his mouth – like chalk and nausea tangled in his throat.

He set the glass down and walked away.

Didn’t eat. Didn’t say goodnight.

He didn’t want Donnie to look at him too long. Not like this. Not when he still felt the phantom ache of that pipe to his ribs, the one that had sent him reeling for far too long in that alley earlier. Not when he knew the sluggishness in his limbs hadn’t left, even after hours.

It wasn’t a wound. Wasn’t blood. Wasn’t bruises.

That scared him more than anything else.

He felt Donnie’s eyes on his back as he slipped into the hallway, tried not to imagine the look on his face. That subtle furrow of his brow. That twitch at the corner of his mouth that meant he was already thinking too hard about something.

Raph made it back to his room and shut the door, leaning against it just a little longer than necessary. The silence inside felt too loud now. The way it always did when his brothers got too close to seeing something he wasn’t ready to say out loud.

He should’ve eaten something.

Should’ve played along with the teasing.

Should’ve said something.

But instead, he just crawled back into bed, not bothering with the blankets. Stared up at the ceiling with a dull, distant ache and a body that refused to feel like his.

His untouched water still sat on the counter.

Chapter Text

The night air tastes like oil and storm runoff. It’s heavy in his throat, dense and wet, and for some reason, it’s harder to breathe tonight.

Raph doesn’t question it.

He’s perched on the edge of a broken billboard, crouched in cracked armor that’s seen better nights. The Nightwatcher’s helmet sits securely on his head, his bandana shoved into a pocket. A slow ache burns under his ribs. His knees feel like someone took a bat to them earlier. And maybe someone did , but if they had, he doesn’t remember.

He doesn't remember much right now, actually.

Just that some low-level thugs have been shaking down folks in this neighborhood. And that he’s not gonna let them keep doing it.

He’s the only one watching. The only one doing anything .

So when he spots them below – three goons outside a corner bodega, hassling some poor guy and his kid – Raph drops into the alley without a second thought.

It’s a blur, at first. Muscle memory and brute force.

He lands hard, the shock jarring through already-aching joints. The bat in his hand whistles through the air, cracking against the nearest thug’s arm. The second guy pulls a knife. Raph kicks him in the chest – too slow. The guy nicks his side. Raph barely feels it.

The third one? Bigger. Stronger. Faster.

Too fast.

Raph misjudges a swing. Gets caught across the jaw. The world tilts , his vision doing this weird double-thing as he crashes into a wall. The armor on his shoulder cracks. So does something in his back.

Pain flares, white-hot and deep. That one’s not normal.

His body won’t move the way it should. His limbs are sluggish , heavy, like they’re working underwater. His grip fumbles around the handle of his weapon. The world rings in his ears.

For a split second, something flits across his mind: what if I don’t get up this time?

He snarls and does it anyway.

They run. Cowards. He won, technically. But it doesn’t feel like winning.

He staggers into the alley, ducking behind a dumpster, sucking in air like it might help. His side is bleeding. Not bad, but enough to stain the armor.

Maybe it’s just old injuries.
Maybe I’m just tired.

His hands are shaking.

His vision is still wrong.

But Raph tells himself it’s just adrenaline wearing off. That’s all. He just pushed too hard. Again. Like always. Like he’s supposed to.

~~~

The lair is quiet when he gets in. Good. That means no one’s awake. No Leo with disappointed eyes – not that he was even home to begin with. No Donnie interrogating him with questions. No Mikey watching him with soft, knowing concern that cuts worse than any blade.

He dumps the helmet, peels off the cracked armor, and flinches when he pulls at the cut on his side. No medbay. He’ll clean it in the sink.

His knees buckle in the hallway.

Just for a second.

He laughs. Or coughs. He’s not sure.

Then he’s in his room, lying in the dark, muscles locking up one by one. His hands feel numb. He can’t feel his toes. He’s freezing, even though it’s summer.

Still doesn’t think anything’s wrong.

Still won’t say anything.

He must’ve dozed off at some point.

Or maybe he just blinked too long, lying motionless on top of the blankets, still in half his gear with a towel pressed against the shallow cut on his side. He hadn’t meant to fall asleep like that – not that he really had . The pain was a dull, distant echo now, buzzing beneath the haze of everything else weighing him down.

The knock at the door is gentle.

Too gentle.

“Raph?” Mikey’s voice is muffled. “You up, bro?”

Raph doesn’t move. Doesn’t speak. Holds his breath, just in case playing dead will work this time.

It doesn’t.

The door creaks open a second later.

Mikey’s silhouette fills the doorway, backlit by the warm hallway light. He’s wearing some ridiculous pajama pants, they’re blue with little pizza slices on them. He’s  holding a bowl of popcorn the size of a basketball.

“I got movies ,” Mikey announces, as if that alone should be enough to summon the dead. “Donnie’s coming too. Said if he has to explain what a power button is one more time, he’s gonna start throwing hands through the screen.”

Raph grunts. A non-answer. It’s the best he can offer right now.

“C’mon, man. It’s your pick tonight. We’ll even watch that dumb action trilogy you like- the one where everything explodes and no one talks about their feelings, like, ever.” Mikey snorts. “You love that one.”

Still no answer.

Mikey steps closer, his tone softening. “You okay?”

Raph finally shifts, turning his face into the pillow. “Just tired.”

He says it low. Raw. Like if he says it any louder , it might crack open into something worse.

Mikey hesitates. Then, quietly: “You sure?”

“…Yeah.”

There’s a beat. Then the rustle of Mikey putting the popcorn down by the nightstand.

“Aight. I’ll save your spot on the couch,” he says, pretending to buy it. Pretending not to notice how Raph hasn’t even rolled over. “Just in case you change your mind.”

The door clicks shut again, and Raph is alone.

But the minutes blur into hours.

Raph lies still in the dark, counting every creak of the lair. The hum of pipes. The distant laugh from the common area. Donnie’s voice, too faint to catch. Mikey’s laughter. The low rumble of a movie starting.

His chest is tight.

He’d meant to go. Swore he’d just rest his eyes for a second, then get up, maybe make some dumb comment about Mikey’s popcorn choices or the lack of real stunts in Donnie’s “highbrow” picks. He’d been halfway to standing up.

And then the pain hit.

A heavy, dragging ache in his joints like cement had been poured into his bones. His head swam. His gut churned. And the exhaustion. God, it was monumental , not the kind you could shake off with a brisk walk and a “suck it up.”

He didn’t even remember lying back down.

Just the shame that followed.

His limbs feel like they’re made of stone. He can’t tell if he’s freezing or burning up. Every position hurts. His muscles twitch like they’re misfiring. His head pounds , and his throat tastes like rust.

But what hurts more than the body is the brain.

That gnawing voice: Why are you like this? You’re supposed to be the strong one. You can’t even keep your eyes open without the room spinning.

He presses a fist against his mouth to muffle the shaking breath.

He’s so tired.

But sleep doesn’t want him tonight.

And Raph can’t figure out whether that’s a curse or a blessing.

Chapter Text

The Nightwatcher helmet stared back at him from its place on the workbench.

Raph stood still, shoulders tense, heart pounding like it was already halfway through a fight he hadn’t started yet. The thick armor lay in pieces beside the helmet – greaves, gauntlets, chestplate, belt. A routine he could normally slip into without thinking. A second skin he used to crave.

Now? Just looking at it made his joints ache.

He sat down slowly, easing onto the bench like an old man twice his age. His muscles pulled tight with every motion. The undersuit stuck to his skin, damp with sweat despite the chill in the air. He hadn’t even moved yet.

The pain was everywhere. In his knees, his wrists, deep in his spine. The worst was the buzzing pressure behind his eyes, like a warning siren no one else could hear.

He blinked slowly. Reached for the chestplate. Lifted it halfway. His hands shook. He barely made it over his head before he had to drop it, the weight forcing a sharp grunt from his throat.

"Come on," he whispered to no one. "Just suit up. You’ve done this a hundred times."

His body didn’t care. His fingers fumbled the straps, breath growing shallow as his lungs failed to draw in enough air. His heart kicked up again, panicked and sluggish all at once. Like it couldn’t decide whether to sprint or seize.

This was getting worse.

It wasn’t just the pain anymore. It was the exhaustion that never left. The nausea, the shaking hands, the bruises that took weeks to fade. The way food didn’t taste right. How sometimes, when he stood too fast, the world tilted just enough to make him second-guess his footing.

And still, he told himself every night: Tomorrow will be better.

He sat back again, chestplate abandoned beside him. The helmet stared on in silence.

“…Maybe it’s not just me being tired,” he said aloud. Saying it out loud didn’t make it easier to believe. “Maybe... something’s wrong.”

The words didn’t feel real, not yet. But they lingered . Pressed against the back of his throat like they wanted to be repeated. To be shared.

He stood slowly – everything hurt – and made his way toward the door.

Donnie. If anyone could help, it was Donnie. Even if he was busy, even if Raph didn’t have the words. He just needed to talk. Needed someone to tell him it wasn’t all in his head. That he wasn’t going crazy.

Just one conversation. He’d do it tomorrow.

“Tomorrow,” he murmured. “Yeah. I’ll talk to Donnie tomorrow.”

But the universe had a funny way of rearranging plans.

Because the weeks that followed blurred together like ink in water – quick, chaotic, and impossible to separate.

Leonardo’s return had thrown the lair into motion again, shoving aside whatever quiet patterns they’d all settled into during his absence. There hadn’t been any time – not for conversations, not for reflection. One day he was considering telling Donnie something was wrong, and the next, he was standing on a rooftop with Leo’s blade against his sai.

Then came Winters. The ancient billionaire and his stone generals. Monsters loose in the city. Nights filled with fighting, close calls, and uneasy alliances. Raph had barely caught his breath between it all. He didn’t have to. No one expected him to.

And when it ended – when the final statue crumbled and the world spun on like it hadn’t nearly been ripped open again – all that was left was exhaustion and silence. His gear from the Nightwatcher days was tucked away, collecting dust. The helmet sat on Splinter's trophy shelf. Leo was home now. Things were meant to feel right again.

But they didn’t.

If anything, Raph felt more out of sync than ever. The ache in his bones hadn’t gone away. The weight in his chest still lingered. And now, with Leo back in the picture, the thought of bringing any of it up felt... impossible.

So he didn’t.

~~~

The rooftops blurred beneath them, metal and gravel crunching underfoot. New York’s skyline was a familiar sprawl of concrete and neon, but tonight, the lights were too bright, the wind too sharp, the jump between buildings too far.

Raph felt it in his knees – the grinding ache that never fully eased anymore. Every impact rattled his bones. His lungs burned cold in his chest, too tight, too shallow. He couldn’t catch his breath. Hadn’t been able to all night.

“Loose ends,” Leo had said. “Just a quick sweep. Make sure no monsters or ancient statues are lurking around.”

Just a sweep. Raph had nodded. Said nothing. He’d hoped that if he didn’t speak, didn’t push back, no one would notice how his hands had trembled as he wrapped his bandages, or how long it took to slide his pads on. He’d hoped he could fake his way through one more night.

But the truth was: he was struggling just to stand.

Mikey was ahead, bouncing across rooftops with the kind of energy Raph used to have – the kind that burned too bright and too fast. Donnie moved steadily beside Leo, scanning their surroundings with that handheld tracker of his. Leo took point like he’d never left.

And Raph? Raph lagged.

“Hey, Raph!” Mikey called back, crouched at the next ledge. “You good back there?”

Raph forced a nod. “‘M fine.”

His voice didn’t carry. His limbs didn’t either. He landed wrong on the next jump – not enough push from the leg, not enough balance – and his foot twisted under him. The jolt of pain was sudden, sharp, blinding.

He dropped to one knee. Gritted his teeth.

Didn’t scream.

Didn’t make a sound.

The others didn’t see – not at first. They were too far ahead. Raph braced a hand against the rooftop, head low, heart slamming in his ears. He tried to stand again and failed.

Shit. Not now. Not here.

He squeezed his eyes shut. Everything ached. His body was overheated and shivering all at once. He could feel the pulse behind his eyes, the pressure rising – like the world was closing in. Or maybe it was just his chest tightening again.

Footsteps.

“Raph?”

Donnie.

Of course it was Donnie.

He was the first to notice, the first to reach him, skidding to a stop beside him. “Hey- hey, what happened? What’s going on?”

Raph didn’t lift his head. He couldn’t. His fingers clenched into the grit of the rooftop. “Just… dizzy. M’fine.”

“Bullshit.”

The word wasn’t a bark. It wasn’t yelled. But it was sharp – sharper than Donnie usually allowed himself to be.

Raph blinked. Shakily looked up. Donnie’s expression was a warzone: horror colliding with fury, guilt twisted into fear.

And beneath it all, the realization was settling in.

He knows.

“You’re burning up.” Donnie pressed the back of his hand to Raph’s forehead, ignoring the way Raph flinched and tried to smack his hand away. “You’re shaking. Your breathing’s-” He cut himself off, jaw clenched tight. “How long.”

“What–?”

“ How long, Raph. ” Donnie’s voice cracked, desperate now. “How long has this been going on?”

Raph didn’t answer.

“Don’t-Don’t do this, ” Donnie snapped. “Don’t shut down on me right now. Talk to me. Please.”

Mikey and Leo landed nearby, tense and confused, but Donnie held up a hand – stay back . This wasn’t for them. Not yet.

Raph couldn’t meet his eyes.

Donnie knelt lower. “Your appetite’s been off. You’ve been losing weight. Bruises that don’t heal. Fatigue. You’ve stopped sparring. You haven’t been sleeping- have you? ”

Still, Raph said nothing. He didn’t need to. It was all there, written across his face, in the way he hunched into himself, tried to hide inside his own shell.

Donnie’s hands shook. “You should’ve told me.”

“I didn’t know,” Raph muttered, and it came out cracked and hoarse. “Didn’t think it was anything.”

“You didn’t think waking up hurting every day was anything? Raph, are you hearing yourself?”

“ I didn’t want to be a burden! ” Raph suddenly snapped back, voice loud and raw-too raw. “You were busy. You and Mikey, you were-were doin’ your own things, and Leo wasn’t even here, and-”

“And what?” Donnie’s voice dropped, cold and fragile. “You thought suffering in silence was better?”

“...yeah,” Raph admitted.

It was the worst answer Donnie could’ve heard.

He sat back on his heels, hands in his lap, staring at Raph like he didn’t recognize him. “You could’ve died tonight.”

Raph flinched.

“I’m serious, Raph. I-I don’t know what’s going on with your body, but it’s not something you can keep ignoring. You’re not just run-down. This is… something’s wrong. And I should’ve seen it, but you made it so easy not to.”

Raph couldn’t look at him. His vision blurred. He bit the inside of his cheek until he tasted blood.

“I’m sorry,” he whispered.

Donnie blinked. “What?”

Raph shifted his weight, visibly trembling. “I’m sorry,” he repeated. Quieter this time.

“For what?”

A pause.

Raph didn’t say.

Just bowed his head.

It wasn’t just for tonight. Wasn’t just for the collapsed patrol or the bruises or the way he hadn’t spoken up. It was for everything . For not being strong enough. For being sick. For being a disappointment. For making them worry.

For existing.

Donnie stared at him, chest twisting. He wanted to scream. He wanted to hug him. He wanted to crawl inside Raph’s bones and force him to see that none of those things were true.

But he didn’t do any of that. Not yet.

He just reached forward – careful, slow – and pulled Raph into him.

Raph resisted for a second. And then he just let go.

Collapsed in his arms.

Breathing hard.

Silent tears falling.

And in the distance, the city went on like nothing had happened.

But for them?

Everything had changed.

Chapter Text

They got him home.

Donnie’s arm stayed around Raph’s shoulders the entire time. Firm, grounding, supportive in a way that made Raph feel like dead weight.

He hated it.

He hated how small he felt, how fragile. Hated how Leo kept shooting glances at him over his shoulder like he expected Raph to collapse again. Hated the quiet that hung over Mikey, how the younger turtle didn’t fill the silence with goofy quips or dumb impressions.

They were walking on eggshells.

Because of him.

“Careful with that step,” Donnie muttered beside him, adjusting his grip as they descended the ladder into the lair. “Lean on me.”

“I’m fine,” Raph rasped.

“You’re not. ”

The moment they were inside, Donnie didn’t let him so much as breathe before steering him toward the lab. Raph protested, but one glance at Donnie’s expression shut him up.

That look was back.

The one that said I love you, but if you lie to me again, I’m strapping you to the exam table.

The second Raph was seated on the padded bench, Donnie was moving , snapping on gloves, grabbing scanners, pulling up monitors. He worked fast. Focused. But beneath the practiced movements, his hands trembled.

Leo lingered by the doorway, arms crossed. Watching. Waiting.

Mikey hovered nearby with a blanket in his arms, awkward and uncharacteristically quiet. He tried offering it to Raph with a small smile.

“I uh… brought this. Thought maybe you’d… y’know. Want it.”

Raph blinked. “...Thanks, Mikey.”

He took it. Clutched it around his shoulders like a shield.

Donnie finally broke the silence. “You’ve had these symptoms for a year?”

Raph’s jaw clenched. “Yeah.”

“You didn’t think to say anything?”

“I didn’t know, Donnie! I thought I was just tired, or overdoing it!”

Donnie's eyes didn’t leave the screen. “Even when the pain started?”

“I didn’t want to bother you!”

The snap echoed in the room.

And it was dead quiet again.

Until Donnie stepped back from the monitor. Took a deep breath. Pressed his palms flat to the metal counter behind him.

“You’re my brother,” he said softly. “you’re never a bother.”

Raph swallowed. Hard.

“I should’ve seen it,” Donnie continued, eyes cast down. “All those little signs- I should’ve put it together .”

“You were busy.”

“That’s not an excuse.”

Mikey’s voice finally cracked the silence. “Is he… like… is he gonna be okay?”

Donnie didn’t answer right away. He glanced at the initial readouts – heart rate, core temperature, blood oxygen. All off. All bad.

“I don’t know yet,” he said honestly. “But I’m going to find out.”

He looked at Raph again. Not with frustration. Not with disappointment.

Just quiet, steady determination.

For the first time in weeks – months, maybe – Raph felt something shift. Like a weight he didn’t realize he’d been dragging had been lifted just enough to breathe again.

Maybe it wasn’t fixed.

Maybe it wouldn’t ever be.

But he wasn’t alone.

Not anymore.

~~~

Raph was fading.

The bench beneath him might as well have been made of glass for how cold it felt, and the pressure in his skull had started to pulse behind his eyes in time with his heartbeat. He sat slouched forward, the blanket Mikey brought still around his shoulders like armor, and tried not to flinch every time one of Donnie’s scanners beeped.

He hated this. The prodding. The questions. The way Donnie kept glancing between him and the screen like he was assembling a jigsaw puzzle he didn’t know had missing pieces.

“How long has your appetite been off?” Donnie asked, cursor flicking across a log file on the monitor. “And I mean consistently. Not just after patrols.”

“Dunno,” Raph muttered. “Months, maybe. Not like I was counting.”

“Muscle tremors?”

Raph shrugged. “Sometimes.”

“Fatigue?”

“I thought I was just lazy,” he grunted.

Donnie didn’t smile. He didn’t even look at him this time. Just scribbled something down on a tablet, lips pressed into a line so thin it nearly vanished. The lab’s overhead lights buzzed faintly, sterile and harsh, and Raph’s body sank deeper into itself, like his bones were trying to disappear.

A breath left his lungs, long and rough. “Are we done yet?”

Donnie froze.

“I’m tired, man,” Raph mumbled. “I just wanna lie down. I ain’t gonna drop dead in the next hour, right?”

“That’s not funny.”

“It wasn’t a joke.”

Donnie turned then. Really looked at him.

Raph wasn’t trying to be snide or dramatic. He was just exhausted. His shoulders slumped, his skin pale under the green, his eyes sunken – not in that freshly-beaten-up way, but in that worn-thin, slowly breaking way.

And Donnie…

Donnie was a genius.

But he wasn’t a miracle worker. Not yet.

A pause.

Then, finally: “Okay. Fine.”

Raph blinked, clearly surprised.

“You can go,” Donnie said quietly. “I’ve got enough data for now. I can run the rest of the analysis tonight.”

He started pulling off his gloves, voice calm – too calm. “But tomorrow, you’re coming back in here. No arguments.”

“Don-”

“No arguments, Raph.”

Raph gave a small, tired nod. It was the closest thing to gratitude he could offer right now.

He pushed himself off the bench with a hiss of effort. His limbs didn’t want to cooperate. His joints ached with every shift, but Donnie didn’t rush to help him this time. He stood back, arms crossed, watching with that look again – the one Raph was starting to hate.

When he finally reached the lab door, Raph paused.

“…Thanks,” he said, voice rough. “Y’know. For… not makin’ me stay.”

Donnie nodded, once. “Get some sleep.”

“I’ll try.”

Raph disappeared into the hallway, footsteps soft.

Donnie stood there long after he was gone, staring at the monitor still running his vitals.

The screen pulsed—too fast. Too erratic. The data didn’t lie.

Something was wrong.

He turned to the main console and sat down slowly, like the chair was going to give out underneath him. His fingers hovered over the keys.

And then he got to work.

Donatello didn’t sleep that night.

He hadn’t intended to stay up all night – he knew better. But the second Raph stepped out of the lab, hunched and hurting and too proud to let it show, Donnie had sat down at his desk and the hours had slipped through his fingers like sand.

Now, at god-knows-what-o’clock, he was still there.

The screen burned into his retinas, pixelated vitals scrolling like endless equations. Charts, projections, potential causes. Blood anomalies, cortisol spikes, suppressed immune responses. Every variable was staring him in the face – and none of them made sense.

“Come on…” he muttered, leaning back with his fingers pinched over his brow. “Just give me something. Anything.”

Another dead end.

He dragged a hand down his face, clawing at the fatigue that tried to settle in. His lab was quiet except for the gentle hum of electronics and the muted tap-tap-tap of keys. Somewhere overhead, pipes groaned faintly with the shift in pressure. The lair was asleep. So was the world.

But not him.

Because Raph’s stats weren’t just abnormal. They were spiraling. And the only reason his brother hadn’t completely collapsed yet was probably the same stubbornness that kept him on his feet, night after night, pushing his body through pain and pretending nothing was wrong.

Donnie knew denial. He’d studied the human psyche, the protective mechanisms of the brain. He’d watched others do it. He’d done it.

But seeing it hollowing out his brother in real time? That was something else entirely.

He pulled up the muscle enzyme readings again. Elevated. Consistently. Along with erratic liver function, recurring fever spikes, and a fatigue marker that looked more like a slow landslide than a warning.

Something chronic. Systemic.

Possibly degenerative.

Donnie's hands hovered over the keyboard.

No.

No, he couldn’t think like that. Not yet.

He exhaled, long and steady, and rubbed the tired ache from the corners of his eyes. He wasn’t done. Not even close. He’d promised to fix this.

And Donnie didn’t break promises.

~~~

Raph was still awake.

He’d been staring at the same spot on the ceiling for over an hour now, the shadows from the vent light creeping across it like molasses. His joints ached. His legs wouldn’t stop twitching. Every time he closed his eyes, it was like the pressure in his chest got tighter—like he was drowning in it, somehow.

So eventually, he gave up.

With a groan, he sat up and swung his legs over the side of the bed, wincing as his feet touched the cold floor. His body felt like it was made of lead, but lying there was worse. Too quiet. Too heavy. Too everything.

He opened his door, hoping not to creak the hinges too much, and padded into the hallway.

Light spilled faintly from the common room.

He blinked against it.

And there was Mikey.

Curled up on the couch, hoodie too big and popcorn bowl half-finished in his lap, eyes glued to the screen in front of him. Some cheesy monster flick was playing—the kind with bad CGI and dramatic screaming and way too much slow-mo.

Raph paused in the doorway.

He’d shot Mikey down earlier. Didn’t even try to soften the blow. But there the guy was anyway, watching movies alone, no complaints, no drama.

Just waiting.

Mikey noticed him after a moment and gave a lazy, lopsided grin.

“Hey, sleepyhead,” he whispered, patting the seat beside him. “Monster movie number three. Plot's nonsense. Explosions are good, though.”

Raph didn’t speak.

He just walked over and sank down beside him with a groan, one hand pulling the blanket over both their legs.

“…Took you long enough,” Mikey said.

Raph huffed, a ghost of a smile tugging at his mouth. “Shut up.”

And Mikey didn’t say anything else. He didn’t ask what was wrong or why he couldn’t sleep. He just leaned his head against Raph’s shoulder and pressed play again.

On screen, something exploded in glorious, low-budget chaos.

And for the first time in what felt like days, Raph let himself breathe

The flickering light from the TV bathed the lair in dull, shifting color, casting vague shadows across the walls. Mikey didn’t speak again. He didn’t need to. The hum of the old movie, the distant creaks of the underground, and the warmth of the blanket over their legs said enough.

Raph let his head fall back against the couch cushion.

His eyes stayed open for a while. Watching the nonsense on screen, tracking every movement in the frame, even if none of it registered. His body still throbbed — not in sharp, stabbing ways, but that low, dull thrum that wrapped around his limbs and settled in his spine like it was never going to leave.

But it wasn’t as bad here.

Not with Mikey’s steady presence beside him. Not with the soft lull of explosions and overacted screams.

The pain hadn’t vanished. He hadn’t miraculously recovered. But the pressure that gnawed at his insides – the guilt, the self-loathing, the sense of failing everyone around him – had quieted just a little.

Maybe it was the warmth.

Maybe it was Mikey’s rhythmic breathing, slow and even.

Maybe it was the simple fact that no one was expecting anything of him right now — no fight, no patrol, no pretense.

Just be here.

Just be.

He blinked slowly. His eyes felt heavy. Sandpaper-laced.

“You still awake?” Mikey whispered without turning.

Raph made a sound — somewhere between a grunt and a breath — that could've meant anything.

“…Cool,” Mikey replied, voice low, almost like he was talking to himself now. “You can fall asleep if you want. I’ll keep watch.”

There was a small beat of silence. Something warm pulled tight in Raph’s chest.

“I ain’t a kid,” he mumbled, voice rough with fatigue.

“I know,” Mikey said. “You’re Raph.”

That… didn’t mean anything.

But it also meant everything.

Raph didn’t reply. He closed his eyes instead, just for a second. His body sank deeper into the cushions without him really meaning to.

He didn’t remember when his head tipped towards the top of Mikey’s head.

Didn’t register when the sound of the TV faded into white noise.

But at some point, the tight coil of tension in his muscles unwound just enough to let sleep steal him under.

And for once, it wasn’t the restless, shallow kind filled with half-dreams and aching limbs.

It was quiet.

Not painless – not yet. But peaceful.

And in that tiny moment, Raph didn’t feel like a burden. Or a failure. Or someone who had to hide the cracks in his armor.

He just felt like a brother.

One of four.

Still here.

Still held.

Still loved.

Chapter Text

The lab was quiet.

Too quiet.

No clanging, no tapping keys, no humming circuits. Just the low mechanical whir of machines idling and the faint buzz of fluorescent lights overhead.

Donatello startled awake in his chair, the faint crick in his neck barking as he jerked upright. His notes were a mess beneath him – half-formed thoughts, numbers that blurred together, ink smudged from where his head had rested against the page. He blinked at the last few lines of scribbled data, trying to recall where he’d left off.

Oh. Right. Blood toxicity levels.

Raph's.

Donnie scrubbed a hand down his face and groaned. He hadn’t meant to fall asleep. He rarely did, but… he’d been at this for hours now. Cross-referencing symptoms, mutagenic factors, environmental triggers, stress markers, everything – looking for anything that could be the root of what was eating away at his brother. Something systemic. Something sinister. Something fixable.

But the more he dug, the more hopeless it felt.

A low alarm chimed from the centrifuge, breaking the silence.

Donnie shut it off, numbly reaching for the printout. He skimmed it, heart sinking at the numbers. Still inconclusive. Still no definitive answer. Just more puzzle pieces that didn’t quite fit.

He stood slowly, bones cracking in protest as he stretched. Maybe… maybe it was time to check on Raph. See if the blood draw from last night had worn him out more than usual. If he was even still asleep at all.

The door to the lab clicked quietly behind him as he stepped into the hallway, soft-footed and tired.

He went to Raph’s room first. Gave a gentle knock, then slowly pushed the door open.

Empty.

No blankets tangled. No lump under the covers. No sarcastic grumbling about being woken up for ‘nerd nonsense.’

Donnie frowned, quietly pulling the door shut again.

He padded through the lair, checking the bathroom, the kitchen.

Then he saw it.

The faint glow of the still-on TV.

And there – curled awkwardly on the couch, blanket half-draped over his shell, head leaning into the cushions – was Raph.

Fast asleep.

And for once, his face wasn’t twisted in discomfort or tension. He wasn’t clenching his jaw, or tossing and turning, or pretending he wasn’t in pain when his whole body clearly ached. He looked… soft. Quiet.

Peaceful.

Mikey wasn’t on the couch anymore – probably snuck off to bed during the night – but the second blanket thrown over Raph’s legs was a dead giveaway of who’d been there.

Donnie hovered in the doorway for a moment, fingers flexing against the tablet in his hand. He should wake him. Get another read on his vitals. Ask about the muscle pain, the low-grade fever, the-

But he didn’t.

Not this time.

Instead, he leaned the tablet against the arm of the couch, adjusted the blanket so it covered Raph a little more, and stepped away.

“Sleep in, tough guy,” he murmured softly. “You earned it.”

And for the first time in days, Donnie left the room smiling – exhausted, still worried, but quietly hopeful.

Because maybe they were far from answers.

But at least they weren’t walking this road alone anymore.

The coffee machine grumbled to life under Donatello’s tired hands. It wasn’t that he needed caffeine – his body was fine, sustained by data and momentum and spite – but something about the warmth of the mug in his palms felt necessary. Familiar. Steadying. The soft gurgle of brewing coffee filled the silence of the kitchen.

He didn’t notice Leo at first.

But then-

The faint clink of a spoon in a mug. A slow sip. A quiet breath.

Donnie turned, blinking hard. “You’re up early.”

Leo stood by the far counter, cradling a cup of tea between his hands, steam curling around his snout. His face was unreadable, shadows softening the edge of his features. “Didn’t really sleep.”

“Ah.” Donnie exhaled and nodded like he understood. Because he did.

There was a long pause. The kind that didn’t demand words. Just shared air and weight.

Donnie poured his coffee, took a sip. Bitter. Good.

Leo finally spoke. “Is he okay?”

He didn’t need to specify. They both knew who.

Donnie stared into the dark depths of his mug. “I don’t know.”

“...That’s not something you say lightly.”

“No,” Donnie agreed, voice quiet. “It’s not.”

Leo shifted, placing his tea on the counter. “He seemed... better. This morning. I mean, not okay , but—he was sleeping. On the couch. It’s been a while since he looked that... calm.”

Donnie hummed, his eyes distant. “He couldn’t sleep in his room last night. Ended up watching some dumb movie with Mikey. That probably helped more than anything I’ve done so far.”

“Sometimes comfort does more than science.”

“Don’t start with your zen crap,” Donnie muttered, but it lacked any real heat.

Leo gave a small, dry laugh. “Wasn’t trying to. Just saying... you don’t have to fix it all alone.”

Donnie looked up then. Really looked at him. “You know I do , right? It’s not about pride, or ego—it’s because if I don’t figure this out, no one else can . He’s my brother, Leo. And I missed this. I missed it.”

Leo didn’t interrupt.

Donnie’s voice wavered. “All those late nights. The changes in his posture. His energy. His appetite. The fucking tremor in his left hand– how did I miss that? How did I let it get this bad?”

Leo stepped forward, slowly, resting a hand on Donnie’s arm. “Because you’re not perfect. And because he hid it. We all missed something. Doesn’t mean you failed.”

Donnie swallowed hard, throat tight. “I just... I can’t lose him.”

“You won’t,” Leo said firmly, gripping tighter. “You’re not alone in this, Don. None of us are.”

They stood there for a moment. The coffee cooled between their hands.

And in the other room, the TV still played softly, casting a dim, flickering glow across the peaceful rise and fall of Raph’s chest.

Chapter Text

Donatello returned to his lab after his talk with Leo and he hadn't left since.

Not really anyways.

He’d gone through the motions – mug rinsed, coffee untouched – but his brain had remained down here, anchored to the quiet hum of his equipment and the soft green glow of code scrolling across half a dozen monitors. A makeshift blanket hung half-off the cot tucked into the corner, crumpled like an afterthought. The air smelled faintly of solder and stress.

A still-frame of Raph’s scan was paused on screen. Muscle groups highlighted. Nerve clusters outlined in yellow. A sliver of heat mapping showed one shoulder running hotter than the rest of his body. Again. It wasn't an infection. It wasn’t some kind of poison. And it certainly wasn’t normal.

Donnie sat with his chin in one hand, stylus in the other, tapping it rhythmically against the desk. The latest blood panel was off. Again. Same markers as before – elevated cortisol, jacked adrenaline, weird inflammatory spikes in places that made no goddamn sense.

Like Raph was fighting something, except there was no something to fight.

"You're burning through reserves like you think you're about to throw down with the world..." Don muttered to himself, eyes skimming the numbers again, “but you’ve been asleep.”

He pinched the bridge of his nose.

Sleep wasn’t even resting him anymore.

He leaned back, kicked lightly at the floor to roll across to a different terminal, and pulled up the EEG. Neural patterns erratic. No surprise there – stress triggers, mystic flux, a few residual energy traces from the Arena, still not entirely understood.

Still...

His hand faltered on the keyboard. He stared.

There it was again. That same anomalous waveform. Flickering too fast, too tight. Like a feedback loop in a frayed cable.

Then, a floorboard creaked behind him.

Donnie froze.

Then swiveled slowly on his stool.

Raph stood in the doorway.

He looked like he’d meant to be stealthy – probably didn’t want to interrupt – but he was still wrapped up in the blanket he had earlier while sleeping on the sofa, and one of his arms were poking out of the make-shift cocoon to hold the blanket in place, exposing a shallow scar Donnie didn’t recognize.

“…Hey,” Raph mumbled, voice like gravel and sleep.

Donnie blinked. “You’re up.”

“Guess so.”

“You should still be out cold. You were–”

“I know,” Raph cut in. “I ain’t here to fight.”

He stepped further into the lab, slow, like his joints had rusted overnight. Donnie took him in silently. Shadows still clung under Raph’s eyes. His stance wasn’t defensive, not quite – but he looked like he’d walked into the ring with a ghost and wasn’t sure if he’d won.

“You feel any better?” Donnie asked.

Raph shrugged one shoulder, then winced and immediately regretted it, tightening his hold on the blanket. “Not worse. That’s somethin’, I guess.”

Donnie nodded toward a spare stool. Raph didn’t move. Not at first. Then, with a soft grunt, he wandered over and sat down – his eyes scanning the mess of wires and notes scattered across the desk.

“Didn’t mean to bother you.”

“You didn’t,” Donnie said. And he meant it.

They sat in silence. Monitors buzzed softly. One beeped. Donnie reached to mute it.

Raph finally spoke again, low and gravel-rough.

“You figure anything out?”

Donnie hesitated.

“Sort of,” he admitted. “There’s a pattern. Something’s kicking your nervous system into overdrive. Even when you’re asleep, your body’s acting like it’s under siege.”

Raph didn’t answer right away. His fingers twitched faintly.

“I’m not saying it’s all in your head,” Donnie added. “It’s not. This is real . It’s just... complicated. The data’s inconsistent. Could be autoimmune. Could be neuromuscular. Maybe even degenerative. Honestly, I’ve never seen a case like this. Your system is burning through energy like you’re fighting something twenty-four-seven.”

Raph’s voice was low. “I feel like I am.”

Donnie studied him. “I’m trying to rule things out. MS. Fibromyalgia. Myasthenia. Even thyroid or metabolic disorders. But the test markers don’t line up neatly with any one diagnosis.”

“So what does it line up with?” Raph asked quietly.

“…Nothing clean,” Donnie muttered. “It’s like every system’s misfiring a little – just enough to throw the whole engine off. But not enough to scream ‘this is the thing.’ It’s... frustrating.”

Raph looked at the scan again – like he was staring at a traitor version of himself.

“…So what now?”

“Now?” Donnie reached for a tablet and turned it toward him. “We go back to basics. We build a baseline. Track vitals. Pain patterns. Sleep cycles. Food intake. Try and find the through-line. It’s gonna be a lot of work. Boring as hell.”

“…Sounds real fun,” Raph muttered sarcastically.

Donnie gave a tired grin. “That’s the spirit.”

Raph didn’t say thank you. Didn’t need to.

When Donnie handed him a biosensor cuff and Raph offered his arm without hesitation – that said more than enough.

After Raph left the lab again, Donnie turned back to his monitors and notes.

He frowned. Then that frown deepened.

Creatine kinase? Elevated.
Lactic acid? High.
ATP levels… inconsistent.

He spun in his chair and began pacing. “No. No, that doesn’t make sense.” He started ticking things off on his fingers. “Could be… overtraining. Nutrient deficiency. Stress response.” His voice got quieter with each excuse.

He hesitated for a moment, fingers ghosting over his keyboard, a search query already half-typed.

Mitochondrial…

He paused. “No. That’s rare. Too rare. Besides, he’s too-he wouldn’t have made it through half the things we’ve done if it was that.”

The query was erased. He moved on.

Chapter Text

One week of vitals, then two. Then however long it had been, Raph had stopped counting. Stopped caring.

The lair became quieter, routines pushed aside to make room for charts and sensors and soft blinking lights that never seemed to turn off. Raph’s room was converted – slowly, then all at once – into something halfway between a bedroom and a lab. Not by force. Just... necessity.

Donnie had set up the baseline.

It started with the basics:
Heart rate. Blood pressure. Temperature. Respiration.
Then came the deeper readings:
Neurological scans. Reflexes. Cortisol spikes. Oxygen levels. Sleep cycles.
He’d installed monitors to run silently through the night, charting REM cycles and movement. Infrared to track muscle tremors. Noise filters for any muttered sleep-talk or pain responses.

None of it made Raph flinch anymore.

~~~

“02:12 AM – Elevated heart rate. Spontaneous.”
Donnie’s notes, scribbled across a tablet.
“04:47 AM – Disturbance in sleep cycle. Possible nightmare?”
“Food intake: 34%. Decrease from previous.”

Raph hadn’t said anything about the nausea.
Didn’t need to. They were watching everything now.

~~~

Week 3.

He stopped fighting the morning check-ins.
Didn’t joke. Didn’t argue. Didn’t ask what the results were.
He just sat there, spine hunched, arm out, eyes on the wall as Donnie applied another sensor to his bicep.

A steady pulse ticked through the machine.
Donnie watched the numbers roll across the screen and swallowed hard. They were fine . The numbers were always fine.

~~~

Week 5.

A sharp pain in Raph’s lower back sent him to his knees mid-warm-up. He waved Mikey off before he could help him up.

“M’fine.”

“Your face is pale.”

“Just pulled somethin’.”

He hadn’t pulled anything.

Later that day, Donnie marked a note:
“Muscle spasms. Cause unclear. Monitor.”

~~~

Week 6.

Leo stood in the doorway one night, just watching from the shadows. The room was dark except for the glow of a monitor blinking green at Raph’s bedside.

Respiration: 13 bpm.
Temperature: 36.8°C.
Pain Response: Low.

It was a lie.

Raph turned in his sleep with a grimace. Jaw clenched. Fists curled in the sheets. Leo didn’t move. He just stared at the monitor as if willing it to change. As if something had to show up. Something obvious. Something they could fight.

Donnie walked up behind him, tablet in hand.
“Still no answers,” he said quietly.
Leo didn’t respond.

~~~

Week 8.

Everything blurred together.

Raph hadn’t trained in days. He barely left his room except when Donnie called him out for another scan or Mikey dragged him into the kitchen. Even then, he barely spoke.

Once, he looked down at his hands – visibly trembling – and grunted, “That new?”
Donnie’s breath caught.
“...No. Just stronger today.”

That was a lie, too.

~~~

Week 10.

The baseline was stable.
Everything looked normal.

And that was the problem.

Because Raph was clearly getting worse.

The couch creaked beneath him as he shifted for the third time in an hour, though he hadn't noticed.
Raph wasn’t sleeping. Not really. His eyes were half-lidded, blinking slow, breath shallow and even, like someone trying to trick their own body into thinking they were at rest. But his shell ached. His head buzzed. The blanket Mikey had thrown over him itched like hell, but even that wasn’t worth the effort of moving.

He just… existed. Breathing. Blinking. Waiting for what, he couldn’t say.

Footsteps echoed soft down the hall – light, deliberate. Controlled.
Leo.

Raph didn’t turn his head. Didn’t speak. The footsteps stopped just shy of the couch, and for a second he thought Leo would keep walking. He kind of hoped he would. But instead, there was a sigh. And then the quiet whuff of someone settling on the opposite end of the cushions.

Silence stretched between them like wire. Tight. Tense. Fragile.

Leo cleared his throat. “You, uh… eat anything today?”

Raph didn’t move. Didn’t even blink. “Dunno.”

Leo hummed a soft, uncertain sound, somewhere between acknowledgment and concern. “Mikey made soup. I could-”

“Not hungry.”

“…Right.”
A pause. The TV flickered in the background, volume low and forgotten. Some nature documentary. Something about wolves or lions or some other predator that would never lose its edge the way Raph had.

Leo sat still for a long time. It wasn’t like him. Raph could feel the weight of his gaze – how Leo kept sneaking glances his way, like he wanted to say something but didn’t know how. Or worse – like he did know, but didn’t think he should.

“You look tired,” Leo offered eventually, voice soft.

Raph finally turned his head, just a little. Enough to look at him. His voice came out flat.
“Then stop lookin’ at me.”

Leo looked away.

And for a while, that was it. Just silence. A couch. Two brothers. One of them slowly unraveling, the other trying not to pull too hard on the thread.

Leo didn’t speak again right away.

The silence had changed shape now – less brittle, more… sinking. Like the space between them had filled with something heavier than air. Grief, maybe. Or guilt.

Eventually, Leo tried again. Softer this time.

“…I miss you, y’know.”

Raph didn’t react. Didn’t even blink.

Leo kept talking, slow and careful, like he was placing words on ice and afraid to crack it.

“Not just… this version of you. I mean–I miss you . Before all this. The way you used to light up when you sparred, or got fired up about some dumb horror movie. You used to laugh with your whole chest.”
A beat.
“You haven’t laughed in weeks.”

That time, Raph did blink. Slow. Heavy.

“…Don’t got much to laugh about.”

“I know,” Leo said. Quiet, but certain. “That’s the part that scares me.”

Raph exhaled through his nose. It could’ve been a scoff. Or a sigh. Maybe both.

He stared blankly ahead again, jaw working. “You think I like bein’ like this?”

Leo shifted beside him, something in his posture softening. “No. I don’t.”

“Then stop sittin’ there like I’m broken glass you’re tryin’ not to step on.”

“I’m just trying not to make it worse.”

“Well, congratulations. It already is.”

That landed hard. Leo didn’t speak. Neither did Raph. The tension surged, and then fell away just as quickly, too drained to hold itself up.

“…I feel like I don’t fit in my own skin anymore,” Raph admitted after a long while. His voice was small. Raw. “Can’t train. Can’t help. Can’t even sleep without feelin’ like I’m gonna choke on nothin’. And every time I look at you guys, all I see is how much better everything would be if I just…”

He stopped. The rest stayed caught in his throat like shrapnel.

Leo’s breath hitched so slightly that  most wouldn’t notice, but Raph did. He always did.

“Don’t,” Leo said. Not a plea. Not a command. Something in between. “Don’t finish that sentence. Not with me.”

Raph didn’t. But the thought was still there, pressed between them like a bruise under the surface.

“…I don’t know how to fix this,” Leo murmured.

“Can’t fix what’s already ruined.”

“You’re not ruined.”

Raph said nothing.

Leo sat forward slightly, elbows on his knees, hands clasped together like he was praying even though they never did that.

“I don’t need you to be what you were. I just… need you to stay . However you are. Just stay.”

And for the first time in a long while, Raph’s lip twitched. Not quite a smile. Definitely not a laugh. But something.

“I ain’t goin’ anywhere,” he muttered.
And then, quieter:
“Don’t got the energy to.”

Leo gave a breath of a laugh. Wry. Pained. But real.

“…Guess I’ll take that.”

They didn’t say anything more after that. Just sat there. The couch sagging beneath the weight of too many things left unsaid, and two brothers who – for once – didn’t try to fight it.

Chapter Text

The lab was quiet, but not silent.
Monitors whispered in low electronic tones, screens pulsed with slow waves of light, and somewhere in the corner, a centrifuge ticked out the seconds like an impatient clock.
Donnie sat hunched over the main console, his third mug of coffee cooling between his hands. The steam had stopped rising ten minutes ago, but he hadn’t noticed. His eyes flicked between charts, his mind chewing over data he’d already seen a dozen times.

Heart rate – prone to irregularities or sudden changes, especially after exertion.
Respiration – shortness of breath or rapid breathing even during mild activity.
Blood pressure – unstable, with episodes of low BP causing dizziness, occasional spikes from stress on the body.
Sleep cycles – heavily disrupted; frequent waking, excessive need for naps, and still feeling exhausted despite adequate sleep.

Nothing here explained the way Raph’s shoulders had started to round in on themselves, or the dull gray cast to his skin under the lair’s fluorescent light.
Numbers didn’t match the man.

He pinched the bridge of his nose, let out a sharp breath, and clicked to the next file. Weeks of vitals scrolled by in neat, infuriating order. Too neat. Too normal . Somewhere in there had to be a crack, something he’d missed-

The faint drag of footsteps broke through the hum. Heavy, slow.
Donnie didn’t look up. “You’re up early,” he said, voice neutral.

“Couldn’t sleep,” Raph muttered.

He appeared in the doorway a moment later, shoulders hunched, eyes shadowed. Not angry. Not even annoyed. Just… tired in a way Donnie didn’t have a word for.
Raph didn’t ask what Donnie was doing – he didn’t need to. The screens, the faint smell of antiseptic, the empty coffee cups lined along the desk said enough.

“You’re really startin’ to look like a vampire down here,” Raph said, leaning against the doorframe.
Donnie managed a thin smirk. “Occupational hazard.”

“Mm.” Raph’s gaze flicked over the monitors, but he didn’t step inside yet. The glow caught the hollows under his eyes, made them look deeper. “Find anything?”

Donnie hesitated. His fingers stilled on the keyboard. “…Not yet.”

Raph made a low sound in his throat – agreement or doubt, Donnie couldn’t tell – and finally stepped inside.

Raph didn’t wait for an invitation before dropping into the chair beside the exam table. It was more of a slump than a sit, his knees angled wide, his arms resting heavy on his thighs.

“You ready?” Donnie asked, already reaching for the cuff.

“Do I get a choice?”

“Not if you want me to keep you alive.”

Raph’s mouth twitched, but it wasn’t a smile. He offered his arm, the one without the faint yellow bruising from yesterday’s blood draw. Donnie wrapped the cuff around his bicep, the Velcro tearing through the silence.

“You’ve been eating less again,” Donnie said, not looking at him.

“Not hungry.”

“Mm-hm. That’s not an answer, that’s an excuse.”

The cuff hissed, inflated. Donnie’s eyes stayed glued to the small screen as the numbers blinked to life. Normal. Always normal.

He wrote it down anyway.

“Blood work next,” he said, setting the cuff aside.

Raph groaned, leaning his head back against the wall. “You’re makin’ me feel like a pincushion.”

“You’re a big pincushion,” Donnie said flatly, opening a sterile packet. “You’ll survive.”

The needle slid in clean, crimson filling the small vial in his hand. Raph didn’t flinch – he never did – but his eyes drifted away, fixed on some invisible point on the opposite wall.

“You ever gonna tell me what you think it is?” Raph asked, his tone casual in the way someone sounds when they’re not.

Donnie’s hands stilled just slightly before he withdrew the needle. “Not until I’m sure.”

“You’re never sure,” Raph muttered.

“That’s science,” Donnie shot back, sealing the vial. “You don’t get certainty. You get evidence.”

They didn’t speak for a while after that. Donnie moved through the rest of the checks – reflex test, oxygen levels, grip strength. Every reading stubbornly refused to give him anything useful.

When it was over, Raph slid off the table and reached for his hoodie draped over the chair. “Let me know if you find somethin’.”

Donnie hesitated, then said, “Raph-”

But Raph was already pulling the hood over his head, the rest of his face shadowed. “Don’t worry about it.”

The door shut behind him, and Donnie stood in the sterile glow of the lab, staring at the numbers that told him nothing at all.

When the door clicked shut, the quiet seemed to press in from every side. Donnie’s gaze lingered on the last entry in Raph’s file, the blinking cursor beside a fresh line waiting for him to type something decisive.

Muscle tremors. Fatigue. Cognitive lag. Appetite loss.

All things he could explain away individually. All things that didn’t fit neatly together.

He pulled up a reference sheet, scrolling past the usual suspects – CFS, MS, myasthenia gravis – until his eyes caught on a rarer entry, one he hadn’t really looked into yet.

Mitochondrial dysfunction.

The bullet points read like a list he already knew by heart. The overlap was uncanny. Too uncanny. But…

Donnie exhaled sharply through his nose, shutting the tab.
No. It didn’t make sense. Those cases were rare, genetic, unpredictable. He’d never seen it before. And if he was right, there was no cure.

He didn’t need a maybe like that hanging over everyone’s heads. Not yet.

For now, he typed instead:
“Continue monitoring. No conclusive indicators.”

The words looked clinical. Clean. Safe.

He didn’t write the other thing that was pressing at the back of his skull, the thing he’d caught himself thinking more than once in the past few weeks:

If the numbers keep lying, I’m going to lose him before I even know what’s killing him.

Raph left the lab without a word.
Not out of anger this time, not even frustration, just a kind of bone-deep exhaustion that didn’t leave room for anything else.

The hallway felt longer than it should have, shadows stretching out across the floor like they were trying to trip him. The air was still, but heavy, pressing down against his shoulders until even keeping his head up felt like work.

Somewhere in the lair, he could hear the faint sounds of life. Mikey humming under his breath in the kitchen. The distant echo of a TV turned too low to make out words. The subtle, careful shuffling of feet – someone moving quiet enough that he couldn’t tell who it was.

That was the thing lately. Everyone moved carefully. Talked carefully. Like the whole place was balancing on the edge of the tipping point.

When he stepped into the main room, the conversation that hadn’t been there suddenly wasn’t there even louder. Nobody was looking at him, but he could feel it – the sharp weight of awareness aimed at the corner of their eyes.

Raph sank onto the couch, the cushion dipping under his weight, and reached for the remote. Just for something to do with his hands.
He flipped channels without watching, the static jump of each new frame filling the silence more than any of them could.

He could almost pretend it was normal.
Almost.

But the longer he sat there, the more the air thickened, the more that pretend felt like it was choking him.

The remote clicked again. And again.
Nothing stuck. Nothing felt worth watching.

He felt their eyes on him without looking. Leo in the kitchen doorway, leaning like he had somewhere else to be but wasn’t moving. Mikey stirring something at the stove, way too slow to be normal.

They weren’t talking to him.
They weren’t talking to each other.

Finally, Mikey tried first. “Made you some noodles,” he said, too bright. “Extra garlic, just how you like.”

“Not hungry.”

Silence again. Then Leo: “You’ve barely eaten today.”

“I said I’m fine.”

“You’re not-”

“Leo,” Mikey cut in, tone a quiet warning. “Don’t.”

Raph’s jaw tightened. “Yeah, don’t. Wouldn’t want me gettin’ upset, right?”

Mikey turned, ladle still in hand. “We’re just… we’re just trying to help, Raph.”

“Help?” The word came out like a laugh that had been sharpened to a blade. “You call this help? Hoverin’ over me every second, waitin’ to see if I pass out or forget how to breathe?”

Leo’s eyes narrowed slightly, a frown settling in. “You know that’s not what we’re doing-”

“It’s exactly what you’re doing. You all think I don’t notice? The whispers. The looks. You think I don’t see you tracking me like some damn science project?”

“Raph-” Mikey started.

“Stop.” Raph stood, the couch groaning as the weight lifted. “I’m not some busted weapon you gotta keep in storage ‘til you figure out how to fix it. I’m still me.”

“Then let us-”

“No!” The shout cracked through the room, hard enough to leave the air buzzing. “Stop tryin’ to save me like I’m already dead.”

No one spoke. Even Mikey’s ladle hung frozen mid-air.

Raph’s breathing felt too loud in the quiet that followed. His hands itched for movement, for space , for anywhere that wasn’t here under their eyes.

“I can’t do this right now,” he muttered, and before any of them could stop him, he was already moving toward the exit tunnel.

Leo called after him – something about not going out alone – but it was swallowed by the slam of the outer door.

The river was black glass under the city lights, fractured by wind and the occasional ripple of something moving beneath the surface. Raph sat on the cold concrete edge of East River Park, knees up, arms folded loosely over them. The night air bit at his face but didn’t quite wake him.

He’d been there for hours, watching the water move like it knew where it was going. He envied it.

He used to come farther than this. Used to make it all the way to Brooklyn without thinking about it. Now? A few miles and his legs felt like lead, his back like it had been wrenched in a fight he didn’t remember having.

He hated it.

Hated feeling the limit before he even reached it.
Hated knowing the city still sprawled out there, just beyond him, waiting – and he couldn’t take it.

Footsteps approached from behind, soft but unhurried. He didn’t need to look to know who it was.

Mikey dropped down beside him, legs dangling over the edge. They sat in silence for a moment, the kind that didn’t demand to be filled.

“For somebody who swears he’s not supposed to be walkin’ around much, you got pretty far,” Mikey said eventually, tone light but edged with something else.

“Not far enough,” Raph muttered. “Used to hit Brooklyn without breakin’ a sweat. Now I’m winded just gettin’ here.”

Mikey hummed, letting the words hang between them. “Yeah. I get it.”

“No, you don’t.”

“Maybe not,” Mikey admitted. “But I get wantin’ to push past what you can do. Even when it hurts. Even when it’s dumb.”

Raph’s mouth twitched, not quite a smile. “Guess we got that in common.”

They fell quiet again. The city’s hum filled the gaps – distant sirens, a train clattering somewhere over the bridge, the occasional gust off the river.

“…They don’t mean to smother you, y’know,” Mikey said after a while, voice careful. “Don, Leo… me. We’re just scared.”

“Scared I’m gonna drop dead?”

“Scared we’ll lose you before we even know how to hold on.”

That one landed. Raph stared hard at the water. “…Feels like I’m already halfway gone.”

Mikey leaned back on his palms, looking up at the night sky like the stars might have an answer. “Then I’ll just have to make sure you’re still my brother the whole way. Not my patient. Not my project. Just… Raph.”

Raph turned his head, studying him. Mikey didn’t flinch from the look.

“…That a promise?”

Mikey smiled, it was small, steady. “Yeah. That’s a promise.”

For a long moment, they just sat there, the cold seeping in through their shells, the river whispering below. Raph didn’t say thanks. Mikey didn’t expect him to. But some of the weight between his shoulders eased all the same.

“So…” he said, slow and careful, “how are you really doing, big guy?”

Raph’s head tilted just enough to catch Mikey’s face in his periphery. “I already told you—”

“Yeah,” Mikey interrupted gently, “you told me the ‘I’m fine’ version. I’m asking for the real one.”

Raph let out a long breath, a dry laugh catching in the middle. “You sure you wanna know?”

Mikey didn’t flinch. “Wouldn’t ask if I didn’t.”

The streetlight above them buzzed faintly, casting long shadows over Raph’s hands as he twisted them together. Finally, he muttered, “I feel like I’m bein’… babysat. Like I can’t take a step without somebody checkin’ if I’m about to fall over. I get it, I do . But it’s suffocatin’, Mikey. I’m tired of feelin’ like I’m just–just this… weak version of myself.”

Mikey’s expression softened, but he didn’t rush to fill the space. He just listened, which somehow made Raph keep going.

“And what if I am ? What if this is as good as it gets? No more rooftop runs, no more late-night patrols across half the city, no more-” He cut himself off, jaw tight. “Feels like I’m losin’ pieces of who I am, y’know?”

Mikey’s gaze didn’t waver. “Then we’ll find new pieces. But you’re still you, Raph.”

Raph finally looked at him, really looked. For a second, the knot in his chest loosened just a bit.

“Thanks, Mikey.”

Mikey grinned faintly. “Anytime. Now, think you can make it back without me piggybackin’ you?”

Raph snorted. “You couldn’t piggyback me if you tried.”

“Dude, have you seen these muscles? I totally could!”

“Keep dreamin’, little brother.”

Chapter Text

The lab was quiet, save for the low hum of the computers and the faint buzz of fluorescent lights overhead. Donnie’s eyes tracked line after line of text on the screen, fingers twitching against the keyboard as if trying to keep pace with his thoughts. Lists of symptoms, progression timelines, obscure medical journals – it was all starting to blur into a single, stubborn fog.

He had been here for hours, chasing diagnosis after diagnosis, pinning Raph’s symptoms to one possibility and then the next, only to have each theory crumble under closer inspection.

Yet one tab kept dragging his gaze back. Mitochondrial Dysfunction . It had been sitting there for days, opened on a hunch he never took seriously enough to pursue. Too rare, too obscure. But now, every time his eyes brushed over the words, something in his gut twisted tighter.

With a muttered curse, Donnie clicked the tab.

The medical jargon was dense, the kind you had to chew through before it made sense. But the further he read, the more the fog began to clear – piece by piece, symptom by symptom, the puzzle started falling into place. The fatigue. The muscle weakness. The tremors. The way Raph’s body seemed to be betraying him in slow, cruel increments.

Donnie sat back, suddenly aware of how shallow his breathing had become. His pulse thudded in his ears, matching the relentless scroll of the mouse. It was all there. Every single line might as well have had Raph’s name written next to it.

The realization was a cold, heavy thing, settling deep in his chest.

No. No, it can’t be this.

But it was. Or it was close enough to terrify him.

Donnie shut his eyes, but the words still burned against the back of his eyelids, each one burrowing in until the fear took root – not sharp and immediate, but deep and quiet, the kind that stayed.

Donnie sits back in his chair, eyes burning from hours of staring at screens. The web of notes and references in front of him is chaotic – some hastily scribbled by hand, others typed in rapid bursts, cross-linked to medical databases and niche research forums. His search history has spiraled from generic queries about fatigue and muscle weakness to obscure clinical studies about mitochondrial function, cell metabolism, and disorders so rare they barely get more than a few paragraphs of documentation.

That nagging thought – the one he kept pushing aside earlier – is now impossible to ignore.
Mitochondrial dysfunction.

He mutters it under his breath like it’s a curse.

He’d skimmed past it hours ago. Too niche. Too far-fetched. But every time he looked at Raph in the past few days – the paleness, the way his muscles seemed to fade without reason, the bone-deep exhaustion that sleep never fixed – his mind circled back. And now… now the puzzle pieces fit in a way that makes his stomach churn.

His fingers twitch over the keyboard.
Testing protocols. Biomarker lists. Muscle biopsy procedures. He drags open another document, jotting down what they’ll need:

• Blood lactate and pyruvate analysis.
  
  
• Genetic testing for mtDNA mutations.
  
  
• MRI spectroscopy.
  
  
• Possibly – though the thought makes his gut clench – a muscle biopsy.
  
  

Donnie rubs his temple. None of this will be easy, and definitely not pleasant for Raph. But if his suspicions are right… he needs answers. Yesterday.

He leans back, eyes fixed on the ceiling for a long, heavy moment.
Then he exhales, sharp and determined, and starts prepping his lab for the first round of tests.

Donnie pushed away from the desk and moved through the lab in silence. He began collecting equipment without thinking – drawing needles from their sterile packaging, uncoiling tubing, calibrating the centrifuge. Every sound felt loud in the quiet: the click of a pipette, the hiss of the autoclave.

Halfway through loading a sample tray, he paused, staring at the blank metal.

He should tell Leo. Or Mikey. Someone.

But then he imagined Raph’s face if word got out before he was sure – the flash of betrayal, the crack of anger under hurt. He pictured Mikey’s too-big eyes, Leo’s jaw tightening, Splinter’s silence.

No. Not yet.

Donnie’s hands moved again, methodical and precise, but his mind was already spiraling around the same dark truth. He had to know. And he had to know alone.

The lair echoed as Mikey’s voice ricocheted off of the walls of the sewer tunnels, his voice clearly announcing his arrival with that usual flair of his. “And that’s how you beat an unbeatable claw machine, bro-”
He stops short when Donnie appears almost instantly in the hallway, goggles still perched on his head, hands twitching like he’s been pacing. His gaze fixes on Raph.

“You–lab. Now.”

Raph blinks, still holding the half-finished smoothie Mikey had ‘bought’ him. “...Uh, hi to you too? What for?”

“Baseline update,” Donnie replied, already stepping forward. “Come on, let’s go.”

Mikey tilted his head. “We just got back, dude. Maybe give him five-”

“No,” Donnie cut in, voice flat. “The window’s optimal right now. It won’t take long.”

He didn’t wait for a response – just steered Raph toward the lab with a firm hand at his shell, like moving a chess piece into position.

Leo emerged from the kitchen, brows lifting at the scene. “What’s going on?”

“Nothing,” Donnie said without looking back. The word landed like a door slamming shut.

Mikey frowned, exchanging a look with Leo, but the lab door had already slid shut behind them with a soft hiss. A faint hum started up from inside, accompanied by the muffled rustle of equipment being prepped.

Inside, Donnie gestured for Raph to sit on the examination bench. His movements were brisk, mechanical – as if giving his hands something to do would keep his mind from fracturing.

“Take off the hoodie,” he said, reaching for a tray of vials. “We’re running a couple more tests.”

“…We already did all the tests,” Raph muttered, tugging at the hem.

“I want them again.”

Raph gave him a look but didn’t argue. Something in Donnie’s expression told him this wasn’t a fight he wanted to start.

Donnie moved in a rhythm – precise, deliberate, and stripped of any unnecessary motion. Swabs. Blood draw. A pulse oximeter clipped to Raph’s finger. Then the heavier equipment: a specialized metabolic analyzer wheeled in from the far corner, its cables coiling like pale snakes across the floor.

“What’s this for?” Raph asked as Donnie fitted a mask over his nose and mouth.

“Respiratory exchange ratio,” Donnie replied. His voice was calm, but his hands betrayed him – just slightly faster than usual, a touch tighter on the straps. “Measures oxygen uptake and carbon dioxide output. Among other things.”

Raph didn’t understand half of it, but he caught the “other things” and filed it away.

The tests stacked one on top of the other – blood lactate levels, ATP quantification, muscle oxygen saturation. The last involved cold metal sensors pressed to his skin, their tiny readings fed silently into Donnie’s tablet.

Raph didn’t say much. Mostly because every time he glanced at Donnie, his brother was staring at the data like it was a cliff edge, and speaking felt like pushing him closer to it.

When it was over, Donnie peeled off his gloves and sat down at his terminal. Data flickered across the screen in sterile graphs and neat, jagged lines. He scrolled through them without speaking.

“…Well?” Raph asked after a long stretch of silence.

Donnie didn’t answer right away. He pulled up the mitochondrial assay results, his throat tightening as the numbers confirmed what had been gnawing at him for days. Reduced ATP production. Abnormal lactate spike. Oxygen utilization inefficiency. The pattern was textbook – and damning.

His voice was too soft when it came.
“Raph… it’s mitochondrial dysfunction.”

The words meant nothing to Raph in the moment. Just another complicated diagnosis in a long list of possibilities. But Donnie’s face – the way his mouth pressed flat, his eyes fixed somewhere just past Raph – that told him enough.

“…That bad, huh?”

Donnie swallowed. “It’s… not something we can cure.”

Raph leaned back against the bench, staring at the floor. For a second, the hum of the lab equipment was the only sound.

“How bad’s it gonna get?”

Donnie’s jaw worked, but no answer came. Because any version of the truth felt like a betrayal.

Instead, he reached for another set of vials, already running scenarios in his head – supplements, experimental protocols, ways to slow the progression. Anything.
Because now, he wasn’t just treating symptoms.
He was fighting time.

He inhaled, long and slow, then turned toward the door.
“Stay here,” he told Raph.

Minutes later, the others filed into the lab – Leo in the lead, Mikey hovering near the back. All of them carried the same look: concern masked as curiosity. Donnie didn’t waste time.

“I’ve confirmed a diagnosis.”
The words were precise, clipped. His tablet flickered to life in his hands, pulling up diagrams of cell structures.

“Mitochondrial dysfunction,” he began, tapping a schematic where the tiny bean-shaped organelles sat inside a glowing cell. “Your mitochondria are the powerhouses of the cell-”

“Don,” Leo interrupted gently, “we all paid attention when Splinter tried teaching us this stuff. And to all of your rants. Skip to the part that matters.”

Donnie’s gaze flickered up, then back to the tablet. “In Raph’s case, his mitochondria aren’t producing energy efficiently. ATP synthesis is compromised. That means his cells – especially those in muscles, nerves, and vital organs – aren’t getting the fuel they need.”

Mikey frowned. “So… he’s just tired?”

“No,” Donnie said sharply. “Fatigue is a symptom. This is systemic. It explains the muscle tremors, the decreased exercise tolerance, the cognitive fog, the-” He cut himself off, scrolling to another graph. “It’s progressive. It doesn’t… reverse.”

The air seemed to flatten.

Leo’s voice came quieter this time. “Treatment?”

Donnie hesitated a fraction too long. “Management. Dietary interventions, supplements to support mitochondrial pathways, physical therapy within tolerance. There are experimental protocols, but…” His eyes stayed locked on the data. “…Nothing curative.”

Mikey shifted uncomfortably, glancing at Raph, who was still sitting on the bench, his head bowed.
“So… what? We just… watch him get worse?”

“No.” Donnie’s voice was firm, but the edges frayed. “We slow it. We buy time.”

No one asked how much time.

Raph finally looked up, his gaze moving from one brother to the next. “Didn’t know it’d be this bad.” His tone was flat.

Leo stepped forward, resting a hand on the bench near him – not quite touching, but close. “We’ll handle it. Together.”

Donnie didn’t look up from the tablet. “Handling it means adapting. Training will have to change. Diet, rest cycles, environmental control-”

Raph cut him off with a low growl. “Don’t start treatin’ me like glass.”

“You’re not glass,” Donnie said. “You’re a system running at reduced capacity. And if we want you operational, we have to treat you accordingly.”

The words were meant to be clinical. They landed like a blade.

The silence stretched, taut and dangerous.
Donnie’s tablet screen dimmed to black, leaving only the low hum of the lab equipment.

Raph pushed himself off the bench, slow but steady, brushing past Leo without another word.

Mikey took a step after him, but Leo caught his arm – a silent shake of his head.
Raph didn’t look back.

When the door slid shut behind him, the room felt colder.
No one spoke.

Donnie stared at the dark screen in his hands, his own reflection faint in the glass.
Every calculation he ran in his head ended in the same place.

And for the first time since he’d started this work, he didn’t want to write it down.

Chapter Text

I just wanted to drop by and let y'all know that college has started back up for me, so I haven't been posting because I've been doing my summer college work. (which I TOTALLYYY didn't leave til the last second. Nooooo. Not at allll.)

Uh, after the first week or two back into the college routine, I'll start writing and posting again. Until then, this and my other fics are on hold.

I am open to answering any questions in regards to the fic(s) though. I love yapping XD

Anyways, I hope you all have a fantastic day/night and that you stay safe, I'll see you lot in the next chapter! :D