okay mal headcanon time as I flesh out specifics for this fic:
he formed from some sort of head trauma (among other things), and is the symptom carrier for the ongoing symptoms. which leads into:
all the system have bad vision, but his is particularly bad, especially in one eye. he lost a significant part of his visual field and it's very sensitive to light, which is why he covers it (on top of emo reasons). he's the most prone to migraines after chester.
afraid of heights, even stuff like balance beams and diving boards make him kinda nervous. his vision problems aren't all of it, but they contribute, hard to feel secure when your depth perception is shit and you're already prone to vertigo.
can't deal with his own blood. other people's blood is fine, but his makes him woozy. he hates this but has learned to patch himself up eithout looking too much at it.
extreme phobia of doctors and medical institutions. stems from time in a psych ward when they thought he was schizophrenic and were trying to medicate him for that. miserable time of his life. prison doesn't scare him but that does.
has a drinking problem. refuses to go to therapy or rehab out of fear they'll commit him, plus general stubornness.
awful about taking medication, regardless if it's a prescription or an ibuprofen or even a vitamin. they're on antidepressants and antianxiety meds, but given that he stops them cold turkey until someone else switches in and starts taking them again, he's usually dealing with withdrawals if he fronts for more than a few days.
a total clean freak, especially when he's stressed. borders on unhealthy, but it's a better coping mechanism than the alcohol so nobody says anything.
smokes bc he thinks it makes him look cool and gives him an excuse not to be around people.
tries to play it cool but intensely protective of vito, even if the guy drives him up a wall. not above hurting him but he's the only one who can sorta vibes. he split off of vito and shares a lot of memories of their trauma, has a lot of respect for him (as a protector... not so much as a person). thinks vito should have been host while he was gone instead of mike.
used to be close with svetlana, but when she saw how much harm he was doing to the system and the people around him, most of it on purpose, she cut him off. he didn't react well, and now she's scared of him and wants nothing to do with him. deep down he regrets what he did and wants his friend back, but he'd never admit it. she made her choice.