One might think that Mikey, as headstrong and brash as he is, might turn to Raph to release some steam. Maybe some physical stuff, skateboarding or running out to beat up muggers, pranking Raph.

Mikey actually goes to Donnie. Sometimes Mikey screws up his words, his ability to turn thoughts to language, and of course shiny things will distract him, leading to Donnie snapping at him until Mikey is able to articulate his thoughts.

Emotionally, Mikey has a hard time actually opening up about the really deep hurts. He wants to be outgoing, happy, silly, and carefree as much as possible. When he gets frustrated and angry, it never lasts long. A quick fiery blast and then he's exhausted. But there are times when the darker emotions keep building up, festering, and he doesn't want to be told that he's okay, that he just needs to meditate or punch a training dummy. Sometimes Mike wants to sink himself into logic and psychology and science. Donnie realized this a while ago and he knows how to read those very particular signs when his little brother approaches him.

Donnie will close and lock the lab doors. He will set aside his projects. He will make hot cocoa. He will play soothing music. He will sit Mikey down and they will drink their chocolate and sit in comfortable silence. Mikey will suddenly sigh and fidget with his empty mug, the sign that he is ready to talk. Donnie will set aside the mugs to refill. And Mikey will talk.

Mikey will open up about his fears, his worries, his insecurities. He will talk about how inefficient he feels, that he isn't sufficient enough, that his casual, carefree, worry-free approach will hurt them all in battle, even as he knows he's a powerful, fluid fighter. He cannot control what his brain does. He cannot control saying inappropriate things, mispronounced words, jokes that he didn't mean as jokes; he feels he constantly must grab that part of him and exhaust himself with maintenance. He's been feeling tired lately. He's losing interest in things he loves. Ice Cream Kitty is worried, he says. He doesn't understand why. He feels fine. Just tired. And his head hurts a lot. His muscles ache all the time. His chest hurts like it's hard to breathe, like his stomach is cold. Sometimes he loses his appetite. Sometimes he cannot bring himself to smile, and he must fake it. Sometimes he forgets how to laugh. Sometimes he wants to cry but feels hollow and empty. And sometimes all he can do is cry, in private, in his room, and dark tunnels away from the lair. Sometimes he is too tired to train. Mostly, he worries that he is feeling dark and cold.

Donatello immediately runs all sorts of tests, laptop open to various scholarly sites. He finally settles on Major Depression with anxiety, comorbid to ADHD. He knows they cannot get medication and he's not sure how vital it is. He looks up more holistic medicines. There are teas he can brew that can help boost neurotransmitters and hormones, and talk therapy has proven effective. He will call April and ask her to bring down psychology books.

As he is talking, excitedly, hands moving, mind whirring, Donnie hardly notices that the wan smile on Mikey's face has gotten wider, and the dullness in Mikey's eyes has brightened, and Mikey's fidgeting has turned to stimming. And when he pauses for breath, his arms are full of little brother, who buries his face in Donnie's neck and thanks him, thanks him, and Donnie tears up when he realizes that Mikey is sobbing openly, his whole body shaking.

"I didn't know what it was," Mikey gasps, "I didn't know what to do, I thought I was sick, I thought I was losing my mind."

"No, no, little brother," Donnie murmurs, "You're not losing your mind. You're sick, yes, but it's your brain chemistry, and it can be managed, you can heal in time. I will help you, and April will help, and when you're ready we'll tell Leo and Raph. We'll all help you. It will be really hard for a while, Mikey, but we're here for you. We love you. I love you so much, Mikey, I adore you."

After more talking, it turns out that Mikey's symptoms have been going on for more than three months, that's how well he was able to hide. Donnie gets a little worried at how deep the shadows might have burrowed into his brother's sunshine heart. But Mikey came to him early enough to catch the disorder before anything drastic happened. Mikey does admit to some very recent thoughts of harming himself. He tells Donnie of injuries he'd taken in battle that he never mentioned, decided that the pain made him feel better. Donnie warns him of the dangers and begs him to promise to bring every hurt to the lab, no matter how minor. Mikey makes a tiny joke about Raph freaking out and Leo becoming a mother hen, and Donnie is just relieved to hear Mikey laugh.

They drink more cocoa. Donnie suggests mixing coffee and chocolate, as caffeine will help ADHD and chemicals in chocolate will help mood disorders. He's already discovered some plants from India and Japan and China that they can brew to help increase dopamine and serotonin. He makes a list of things to discuss with April, and maybe even her father. He tells Mikey that depression is a powerful illness in the brain, and it can't be cured but it can be managed, that episodes can heal with help, and Mikey is all sharp eyes and sharp questions and a sharp smile, bright lamplight summer blue irises shimmering with a desire to learn more, to know more, to know as much as he can handle at once.

Inside himself, deep inside, Donnie wants to cry out in happiness and dance on the moons of Jupiter for this chance to share such science with his dear baby brother. They keep talking and Mikey keeps listening. Like an ecstatic child and also like an attentive student in a lecture hall. The look on Mikey's face tells a tale of euphoria and wonder, and Donnie keeps talking until he realizes he is teaching himself as well.

The hours have passed. Mikey has fallen asleep beside him. Donnie feels his heart swell to the size of the universe. Here is his very own sun, and he is sworn to make sure that light and warmth never fade. Carefully, he picks up Mikey and carries him to his own bedroom, almost as cluttered as Mikey's, but with a wider bed and a small ionic air purifier and a pink noise generator. It might ease Mikey's nearly chronic nightmares. They will get to cuddle. Mikey might sleep in peace. Donnie might actually be able to really sleep.

As he places his little brother in his bed, handling him like porcelain, Mikey stirs and sighs. Donnie slips under the covers and draws Mikey's head to his shoulder, holding him close. In his rapidly sinking sleep, Mikey murmurs, "I love you Donnie, you're my brain hero."

Donnie kisses Mikey's forehead and whispers, "I love you, Mikey, you're my heart hero."