because the breakdown of Leo and Donnie's brotherhood in the show is actually kind of devastating

set the night after The Fourfold Trap, back at the end of season 3.

tmnt = viacom

little hounds of blood and rank

It's after Donnie's phone finally buzzes its way off the couch and clatters loudly on the pit floor that Leo finally sighs and gets up to just give it to him, instead of Raph's old-faithful method of 'not my problem'.

Raph who mutters finally as Leo nudges his beanbag with his foot before clambering over the couch and up towards the lab.

Leo is a ninja, and yes he understands that he and his brothers have a sacred trust to not go snooping through each-other's rooms, or snack-stashes, or browser histories, but Donnie's phone is in his hand, and it's vibrating again, and the screen has helpfully lit up, so of course Leo takes a look.

He would never dream of reading any more than the message preview, he's really not that kind of a jerk, but he's still surprised to see Donnie's screen flashing with JONES - 4 MESSAGES, instead of a message from April.

(For all Donnie is a marvel of Zero Tact, Leo is always impressed that in Donnie's phone April is just April, not Princess Chinchilla or Precious Little Murder Aubergine or whatever nickname Donnie's embarrassed himself with that week.)

The lab door is closed over, but Leo nudges it open with the edge of his shell, knocking a knuckle against the frame. Donnie doesn't pay Leo any attention, but Leo is a ninja, and so is Donnie — Donnie knows he's here. He's just busy.

"Hey Donnie," Leo says, leaning against the door. "Message for you."

Donnie looks up from where he's sweeping, then holds up a hand. Leo tosses the phone, and Donnie catches it, snatching it out of the air. It's not as precise as Leo would like, but it's been a long day, and he can give Donnie a break on this one thing.

Leo leans back against Mutagen Man's ice-tank, smirking. "I never thought you two'd be friends, what with your shared interests, and all." He waits for the obligatory rise out of Donnie, and sure enough, Donnie straightens, the broom stilling in his hands. But that's all he does, and so Leo gently nudges the pressure point: "Y'know. April?"

"I know what you meant, Leo," Donnie says, his voice tight as he thumbs back a reply to Casey. The wrong kind of tight. This is Donnie when he's trying not to snap, when he just wants to be left alone, and the wrong kind of alone. Donnie seethes just as much as he explodes, and Leo's not interested in the fall-out from either. "Things change. People grow up."

It's not the kind of response Leo had hoped for, and inwardly, he sighs. So Donnie's still upset about earlier. They don't have time to indulge Donnie and one of his sulks, but the argument earlier almost got really ugly, and they don't have time for that either, not while Karai still roams the streets, mutant and alone.

She needs to come home. Leo needs to bring her home, and give her back to her father. Right now, it's the only hope Karai's got. "Are you still mad about earlier?" he asks.

Donnie doesn't reply. He starts sweeping again, the lab silent except for the scrape of bristle on concrete, and the soft fall of dust.

"Donnie?" Leo prompts again.

"It's been a long day, Leo. Just let me clean up."

Leo chews his cheek, irritated at Donnie's stubbornness, at how he just won't let it go already. "Look," he says, swallowing a mouthful of pride. "Maybe I was a little harsh earlier, but, you can't give up on this, Donnie. You know how much sensei is counting on this — how much Karai is counting on this."

"I know that."

Donnie doesn't look at him; instead, Donnie looks at his clean, freshly-washed beakers, all still a little damp from the sink, with no remnants that Leo can see of the failed experiments from earlier. "So you'll try again tomorrow."

He means it to be encouraging — Donnie had a lack of faith in himself, things got hard, he had a little moment of despair. They've all been there, but they get through. They always do. But Donnie doesn't do what Donnie usually does whenever Leo tries to get through his sulks. Donnie should shuffle, and smile, and say yeah, I guess and then Leo will herd him out of the lab to do whatever, but it's about a second after Leo says "tomorrow" that Donnie's shoulders tighten.

"I can't," he says.

It's the wrong answer, and Leo tells him as much. They don't have time for excuses. Karai doesn't have time for excuses.

"Leo, I can't." Donnie throws a hand out at his desk, and the stack of notes that Leo can't bring himself to care about. Those are Donnie's things. Donnie's supposed to be able to do this. He's done it before, so why can't he do it for Karai? "Don't you think I would if I could? There's something wrong with her, Leo— this isn't just a normal mutation. And I don't know what happened to her; maybe it's something about her DNA, maybe it was something in the mutagen that Shredder threw her into, but until I can figure out what it is that's causing this, I can't fix it."

"But you have to keep trying."

"Until when, Leo?! I'm out of options. When I said to Mikey that this was my last shot, that wasn't a this is the last one because oh boy this is gonna work, go tell the whole family to get in here, it was this is my last shot and then I'm stumped, and—"

Donnie's phone buzzes again, cutting through whatever Donnie wanted to say next. Leo glares at it, the phone scooting along Donnie's desk until Donnie picks it up, turning his shoulder to Leo as he swipes his thumb across the screen and half-smiles at whatever Casey has texted this time.

"Maybe if you weren't texting all the time, you'd have a clue," Leo says drily. Donnie doesn't faillike this. Not for this long. Donnie sees a problem and he digs into it, and he fixes it, and maybe he doesn't always fix it in the way Leo would like, but he does it. That's his job.

Donnie cured all of New York. Donnie cured Mikey, and Mikey cured Donnie. There are ways and methods of reversing mutation — there's no way that Donnie can't not know how to cure Karai.

Donnie's not doing his job, and maybe this is why: Donnie's busy talking to Casey.

Donnie's busy talking to April.

"I'm sorry I'm taking thirty seconds out of the past forty-eight hours to talk to our friends," Donnie snits, and the sheer disobedience boils Leo's gut. Donnie used to fall in line, but there's been a malignant, rebellious strain in Donnie since long before the evacuation to Northampton, and looking back, Leo can see where it's only gotten worse, not better.

But maybe it's always been there.

Well I'm going!

It's always been there.

"Karai needs to be cured. She's out there, and Shredder's looking for her— she's losing her mind, Donnie!"

"Don't you think I know that!?"

"I don't think you care. Not enough, Donnie, or you wouldn't want to give up on her like this."

"Okay," Donnie says, and points to the door. "You can leave now."

"Why? Because I'm right?" Leo asks, ducking his head like he's ready for a fight, anger spreading through his chest and arms like it always does when he's right, and furious to be so. It's the only answer he can think of. Donnie hates Karai; he's never seen the good in Karai like Leo has. "You never liked her, Donnie, you never trusted her!"

"No, I didn't," Donnie snaps back. "There was that whole trying to kill us thing that's a little hard to get past. But," he interrupts Leo before Leo can jump in, "you know who I do like and who I do trust? Master Splinter. You think I'm screwing this up on purpose over some grudge? If I had enough retromutagen to cure every single one of Shredder's goon squad, I'd do it, because it's the right thing to do, so— so if you really think that I would let our father's daughter suffer like this because I don't like her—"

'I don't like her' snips out in the snottiest, most obnoxious mimic Donnie has ever managed mid-argument, and Leo wants to stuff those words back up his nose.

"—then you need to get out of my lab, Leo, before I do something we'll both regret."

Leo doesn't, but it's only self-preservation that stops himself from calling Donnie over-dramatic. "Okay, so if you want to cure her, what's stopping you?"

He genuinely means it as a question — what's blocking Donnie? If it's something Kraang, they can break into TCRI again. If it's something Shredder, they can break into the old church and hold Baxter Stockman down by his wings until he screams the answer. But Donnie bridles, his shoulders tightening and his hands clenching. He takes one slow breath, then another, and then when he speaks it's icily cold: "I'm smart, Leo. I don't think the rest of you understand just how smart I am."

"No," Leo counters. "I think we do — we've kind of known you're some kind of super-genius since we were four. What's your point?"

"My point is that it took me almost a year to make retromutagen, and that was with just the stuff we had to hand. Now, it turns out that the Kraang have a whole herd of monsters making it — so it's not a standardised chemical compound, and Shredder's buying it in bulk to try make his own mutants, and I don't know if there's anything they're adding as part of the process because funnily enough, Karai didn't hand over a handy little sample for me to keep before she spat acid in Raph's eyes."

There's spit in the deeply-lined corners of Donnie's mouth, little bubbles of angry froth, and Leo can see nothing of his brother in the twisted, ugly green face in front of him, except, he can see all of Donnie — all of Donnie's miserable, desperate failures, but none of them reach him, or reach past the tight ball in Leo's own chest of his own problems, his own issues, and his own failings.

Nothing Donnie can say will change the fact — that they're failing Karai, failing Splinter.

"I'm flying blind here! I've got nothing aside from all the science I used for the first batch that isn't working anymore and I can't figure out why. So you feel bad, Leo? All you're doing is moping around and giving the orders. Me? I got about three hours sleep the other night, and then Mikey comes in here again asking what I'm doing, even though I asked him to stay out, and then he goes and drags the whole family in here to watch and I still had to look Splinter in the eyes when it failed. And you feel bad, Leo? You? Really? Look around!"

Leo doesn't, but that doesn't stop Donnie from waving at the giant frozen vat that used to be the Pulveriser, or the life-hacked mini-fridge covered in padlocks, icicles clinging to the chains around it and the MIKEY DO NOT EAT sign duct taped to the door. "You don't know anything," Donnie's voice is almost a hiss. "Not about this. Not about failing Karai, or sensei, or screwing up. Me?" He laughs bitterly. "Ohho, I've got a whole list."

So does Leo, a long litany since that first night topside.

They might actually be the same lists.

But Leo doesn't ask Donnie to compare. Instead, he stares his brother down, waiting for the storm to pass.

"You know what would have been nice?" Donnie asks, after a long, long minute. His voice this time is calm — sad. He rests his chin on the top of the broom handle, and from this angle, Leo can see the miserable little smile on Donnie's face. "Thanks for trying, Donnie. Better luck next time. Instead, I got try harder from someone who sits outside watching TV and brooding." Donnie looks at him, a little helplessly. "You never even asked if you could help."

Leo scoffs. "How can we help? You just said yourself how super-smart you are. If you can't fix this, how can we do anything?"

"Watch the centrifuge," Donnie snaps, whipcrack-fast. "Check the timers, help clean up, count beakers, mark off milestones, watch Mikey — fix the bike so that's one more thing off my list. Change the oil in the Shellraiser, maybe. And you know what, even if there was nothing you could do, you could still have just asked. Taken an interest in this cure for your precious Karai instead of just snapping your fingers and expecting me to click my heels and hand it over."

It's a vicious comeback, barbed with every tiny little wish Donnie's never dared to ask for. Leo was prepared to snot at whatever Donnie came out with next, rolling his eyes or point out how Donnie's just making excuses — but Donnie's got a point, and Leo hates every single correct word that comes out of his mouth. They could have helped. They all just assumed that Donnie didn't want them around — it's not like he's made them welcome; the lab is Donnie's space, and when Donnie is stressed, he snaps and he mutters and he yells, and something blows up and it's only Donnie's temper half the time.

But he's right.

Leo watches TV and trains and makes plans. Mikey goes wandering into the lab and skips out five minutes later with Donnie screaming behind him. Raph punches his bag a few times — but Donnie's the one doing the work.

Which — that's what Donnie does. Leo never considered that maybe he didn't want to be doing it.

And there it is again, an angry wrench in his chest. How can Donnie not want to be doing this work, knowing how much they're all relying on him?

Leo bites the inside of his cheek.

"So, you know why Jones and I are friends?" Donnie laughs, once. It's cold, and it's mean. "Because the day after Speed Demon, he was the one who came out to the barn with a tub of wax for where I'd had spark plugs through my shell, even though we kind of hated each-other. And he and April are the two people who just ask me how's it going without saying do it better."

He holds up the phone; Leo can't see the text on screen, but there's enough of it — trash-talking from Casey, probably, and a reply from Donnie of the picture with the cat hanging over the computer monitor that said STOP POSTING. "Casey wanted to know if I'd ran out of energy drinks, because his dad gets them bulk from the Costco in Queens. And April yelled at me twice last night to go to bed but hey, electrocution kind of adds plus ten to my insomnia roll — and wow she has quite the vocabulary when it comes to bad Mazes and Mutants jokes. When was the last time you and I talked that wasn't about work? And I mean a real conversation."

Leo can't remember.

So he says nothing.

Nothing is enough of an answer for Donnie; he presses his mouth together and huffs out a little sigh from his nose before dragging a hand over his face in the way Donnie always does when he's upset and backing down. "Leo— look, it's been a really long day and all I want to do right now is finish up in here, take a shower, and maybe sleep. Can we talk about Karai some other time? Tomorrow, maybe?"

The words fall out of Leo's mouth, clumsy and unrehearsed: "Sure, Donnie. Can I help?"

He expects Donnie to wave him off: a quiet, warm, ah, no thanks, I got this! or maybe, now that Donnie had called Leo on it, to hand him the broom and put him to work.

Instead, Donnie sighed, and for a moment, Donnie looked different: colder, taller, and a long, long way away. "Yeah," Donnie said, and Leo's gut clenched. "Close the door after you. Thanks."

the end