Prologue: Totally Not Foreshadowing

"You really don't have to be here. I can finish this up on my own."

"I know. But if I leave, you're gonna end up staying awake all night working on it, and then I'm gonna have a real boring time beating your shell in training tomorrow." Raph reaches over with his free hand, giving Donnie's shoulder a shove. Not very hard, just enough to rock him and take the sting out of his tone. The other hand is currently occupied by Chompy; the little space tortoise is fast asleep, and doesn't seem to be bothered in any way by the commotion. He's cradled carefully in Raphael's palm, letting go of tiny smokey snores while the two brothers go back and forth. "So get to it."

Donatello takes the shove in good nature, giving a mild snicker and a half-hearted swat in return before his attention shifts back to the task at hand. Staying up late is definitely not out of the ordinary for him. It's practically routine. Finish patrol, vanish into the lab, work on some project or another for the night, get an hour or two of proper sleep, suck back a few cups of coffee and then jump into training for the day. That's definitely been Donatello's constant for the last week or so, but it may have started leaking into his enthusiasm for their martial arts. Which has led to the intervention of sorts in the form of the hotheaded brother sitting on his desk and berating him. Not the easiest way to get work done by any means, but the company is nice. However snarky it is.

"I thought training was for honing our skills in battle, and not for trying to bury each other into the mats," Donnie returns dryly. He fixes the slide on his microscope and settles back into it, his hands adjusting the focus without really needing to think about it. Multitasking is one of Donnie's stronger suits - Raph can't count how many times he'll be explaining a plan or even just chatting with someone and his hands will be working. It gets really freaky when it involves a blowtorch, because Donnie won't even be watching what he's doing.

"You're not honing any skills if you're asleep on your feet."

"I'd consider that a skill."

"It's totally not a skill."

"Being able to balance on your feet and stay upright while your brain is shut down and recharging?" It's a wonder Donnie's eyes don't just attach to the microscope. One day he'll probably invent little microscope glasses. Won't even need to bring samples home then. Raph raises a brow as the genius continues, half of his attention on the slide he's examining, and half on the friendly argument. "That's not something anyone's born with. That kind of discipline is hard to train into someone. It's totally a skill."

"Yeah, alright." He's got him there. Raph shakes his head with an eye roll, leaning back onto his palm as he glances around the lab. Donnie's probably got seven or eight projects going on in here. There's a half-repaired bit of Metalhead, something that looks like an upgraded smoke grenade, three toasters in a pile that all have the unfortunate skeletal appearance of being massacred for parts. Said parts have all been brought over to another station, which is occupied by not only the old TV remote but a pretty sad looking Gamecube. The console has a kunai sticking out of it, and Raph swiftly pulls his gaze away to look around at everything else instead. Totally didn't have anything to do with that.

It always makes him wonder how Donnie gets so much stuff done in here. The place is never clean, nor is it ever empty. There's a consistent cluttered feel to the whole lab, and yet Donnie somehow knows where everything is. Anyone could come in and ask for something and Donnie would shove his hand into a pile of parts and pull out exactly what they need. He manages to finish a project every few nights. Most are small; repairing remotes, game consoles, toasters. The occasional television. Some are more complex and take time to complete - or on the other hand, are constantly being upgraded so they are never really finished. As soon as one project stops, another starts, with Donatello left in some kind of never-ending spiral between mad scientist and mechanic.

Raphael will never understand how he does it. He really doesn't want to try.

"What're you lookin' at anyway?" Hah. That got his attention. Burgundy eyes snap up from the eyepiece of the microscope and Raph can read the confusion on his face. It's very satisfying to catch his brother off guard, though after another second or two of silence, his satisfaction begins to drip away into self-consciousness. Raph scowls, narrowing his eyes. "What?"

"You're never interested in my projects unless they blow something up," Donnie replies slowly. Fair enough. Most of Donnie's projects are too intricate and involve far too many big words for Raph's liking, so he tries to ignore much of the mumbo-jumbo. Eventually, Donnie stopped really explaining it to him. So for him to ask for it, yeah, guess he deserves a bit of suspicion.

"Humour me."

The darkening scales over Donnie's face catches Raph's attention more than the silence that follows. What bothers him more is when Donnie actively turns his face away, refusing to look him in the eye. He doesn't want to tell him. That's weird. Donnie usually jumps at the chance to dive into a far too complicated sciencey lecture. It really isn't like him to avoid one unless…

Well, unless he's doing something he shouldn't be or it's embarrassing. Unfortunately for Donatello, Raphael is incredibly interested in both of those options. If it's something he shouldn't be doing then it is a wonderful reminder that Raphael isn't the only rebel in the family. And if it's embarrassing, then it's fuel for when he needs something later on. Win-win. Chompy is placed on the desk beside Raph with utmost care as to not wake him. Donnie's shoulder is grabbed in no such way.

"What is it?" He tries his best to keep the excitement from his voice. He fails. He said it didn't explode - actually, he didn't say that. It might still explode. Which could still be really cool. Another option pops into mind and the brief moment of interest is back into wariness, green eyes narrowing once more. "You'd better not be messing around with government stuff again."

"No! Well - not this time. This isn't anything like that. And I can't hack the CIA website from my microscope." You can pinpoint the exact second that it registers as an option for a new project, and Raph does his sorrowful duty of swatting the idea out of the back of Donnie's head. He doesn't need to attach a computer to his microscope when he's got a computer in literally everything else. "Ow!"

"So if it's not illegal and it doesn't blow up, what is it?"

There's that look again. Donnie won't actually look at him but he can read the expression on his face all the same. Raph ponders for a moment and then decides he doesn't like it. It makes him wary and uncomfortable, like when he's the focus of a lecture from Splinter about manners or his anger issues. While he's brainstorming on how to change it, Donnie answers so softly that it takes him a second to register that he's actually spoken, and another to realize what he's said.

"..What?"

"Since creating the retromutagen, we've had a lot of close calls. Too many." Donnie sighs and leans back in his chair, all of the exhaustion from working for so long showing with how his shoulders slump. He tugs his mask down to hang around his neck and Raph can finally see the dark spots under his eyes a moment before the scarred fingers reach up to rub at them. Donatello is spent, but he's still working. Still pushing at it. Raphael knew he was tired, but he didn't expect it to show so plainly on his face. How hadn't he noticed before? "It's only a matter of time before one of us gets hit with either the retromutagen or the normal stuff, and I want to make sure that I can fix both problems."

"Oh."

Oh. Such a stupid response. Try for something better.

"Well, if we get hit with normal mutagen, at least it's easy."

He knows that's a worse response as soon as it comes out of his mouth.

"But it's not!" Donatello's hand hits the table, and Raph scoops Chompy back up into his arms as the alien wakes up with a squeak. Donnie continues after a moment of pause, letting Raph soothe Chompy until he quiets down in his hands. "We're already mutated. If we get hit with retromutagen, and that's even if we did technically mutate a second time, the likelihood of it turning us all the way back into normal turtles is pretty much one hundred percent. Which doesn't solve the initial problem. But it's really hard to tell a chemical compound 'Oh, that's fine, you can stop halfway.' It doesn't work like that."

Raph doesn't even know where to start. So he keeps his mouth shut, making sure he's actually focused on what Donnie's saying. His brother is worked up, and somehow it feels like this isn't just fatigue talking. Donnie lets his hand fall again and then reaches over to his desk drawer, rummaging in it and pulling out one of his journals. The cover is green and has several scorch marks on it, but Donnie opens it before he can read the front cover. The page he opens is full of calculations that Raph's eyes just blur over; there's no way he's able to even begin to understand what all of it means, so he doesn't try to. He just lets Donnie keep rambling, a pen suddenly in his brother's hand and continuing the page as he talks.

"So I need to figure out a way to either a) make a retromutagen that ignores our specific genetic code so that it doesn't turn us back in the first place or b) make a mutagen that takes our genetic code and rebuilds it exactly as it was before. We don't have any of Splinter's human DNA to turn us back if we get unmutated. The only way to do that is to create it artificially or program the mutagen to turn us back into us but it's hard and very time-consuming and I barely know where to start. And if I make a retromutagen that ignores our DNA, then if we do get double mutated, then I don't have any way to get us back to normal at all. It's a problem either way."

All Raph can do is stay quiet for a few seconds, trying to process what his brother is saying. It seems like they're back to their usual argument; Donnie's working himself into the ground because he's worrying for their safety. It's happened before, and it will happen again. Although last time, they had Splinter, and last time it was just a matter of Donnie learning medicine. The entirety of human and veterinary medicine. Which he did, with some intervening from Leo and April so he slept in the meantime, but he did learn it. Donnie can learn anything. That's a fact that Raph will stand by until the day he dies. But if the science isn't there for it… there's only so much that Donnie can create. Unless they find someone who knows more about the mutagen than they do and will actively share it with them, then Donnie's got to figure it out on his own.

Finally Raphael settles on putting Chompy onto his lap, stroking over his chin. His turn to avoid looking Donnie in the eye now. He's going to start talking and he isn't sure it's going to get him anywhere, but it's worth a shot if it makes him feel any better.

"I'm not any kind of sciencey type, so I really don't know how to help you with any of that. But I know enough to say that lack of sleep isn't going to help you figure it out any faster." Raph glances over at him, raising a brow as Donnie gives him an annoyed look. They've told him he needs to sleep more times than there are scales on his body, and its understandable that he's tired of it. But Raph pushes on, returning the look. "It's true. I might sound like Leo, but look at how you're doing in normal training. You're barely functioning. You're missing simple steps in your katas. You're clumsy. There's no way that's any different in here. How are you supposed to figure out detailed scientific formulas if you've been scribbling nonsense on that page for five minutes without even realizing it?"

Hah. Got you.

Donnie's eyes snap down to the journal. Sure enough, his calculations and notes were slowly turning into him writing what he was trying to say, and at the end of it his writing wasn't even legible. The dawning look of defeat on his brother's face is pretty nice. For once, Raph's got the upperhand on the genius, and he's not about to let it go. Donnie glances over the microscope and doesn't say a word, finally reaching around to turn off the light.

He barely gets a chance to turn off the switch before his feet are scooped off of the ground.

"Hgrk- Raphael, put me down! I can go on my own!"

"Nah." Raph swings Donnie around so that his brother is draped upside down over his shell, his knees bending over his shoulders so he can hold his ankles and keep him there. It's a position easy enough to get out of, but it really speaks volumes of how tired Donnie is when he makes no effort. Instead the genius lets his arms flop to the floor in defeat, muttering complaints in Japanese.

"Hey! There are children in the room."

"I'm pretty sure Chompy is older than all of us."

"So? Don't teach him bad things."

Raph glances down just as Donnie turns his head and gives him a strange look. Almost like the one he'd put on when Raphael first asked what he was up to, like he's trying to figure him out. That twisting feeling in his gut is starting up again, so Raph gives Donnie a bit of a bounce to adjust his grip, breaking the eye contact.

He doesn't think too hard on it.

"C'mon, Chompy. Time for bed." Chompy toddles his way up onto one of Donnie's trailing palms and sits, trilling in delight as Raph starts out of the lab. Raph really should get a picture of this, Mikey would love it. But instead, he continues dragging Donnie to the bedrooms, Chompy enjoys his turtle-palm-carpet-ride and Donnie gives a long-suffering sigh.