Gonna compile my Caboose hc's real quick just for ease of access bc. I have to go rummaging through my blog every time I wanna check something I've said. Anyway.
He has gigantism, acromegaly, and human double-muscle mutation (myostatin-related muscle hypertrophy/myostatin suppression)! and while he doesn't need it all the time, he has forearm crutches and a wheelchair to deal with the joint/back pain. His natural voice is actually the deep O'Malley one! He just is chirpy to be less intimidating.
He's Latino - specifically Mexican! I like the think his moon colony city was primarily Latine. (Maybe it's called... Los Pequeño México de la Luna? Maybe it's shortened to Luna México when spoken of casually. Think Los Angeles type shortening. Caboose es un Luna Méxicano. El es del Luna México. It's 500 years in the future and the Moon was settled on in 2080 - there's definitely a moon dialect by now. The moon also has it's own governing body, but that wouldn't stop cultures from culminating together.
Obviously, Caboose autistic ADHD... and brain damage but that part's canon. He doesn't like strawberry icecream bc of the fruit chunks. if it wasn't chunky it'd literally be fine. OH and he's dyslexic!!
Uuuhhh biromantic asexual :) he could fuck if he so desires but he doesn't really think about it.
This is more of a Schrödinger's headcanon but. Huragok/Human hybrid Caboose !! he was built but he is human and also he is full of love and biomachinery and giving robots sentience all the time
He has tritanomaly - green and orange barely exist to him.
He's going to Harvard online, not sure what for yet. IMO he'd probably bounce majors all the time. He wants to learn as much as possible about everything! Learning is fun!
Also uh he's plural. I don't have to explain this it's just true. Makes second secret friends based partially on his real friends (but not on purpose) that live in his head. That's why his echo said hi back :) and why he flat didn't question O'Malley's presence. Like oh hey a new guy what's up? In the same vein, he's got Trauma from being a neurodivergent kid in public school. It's why he got mad enough to bounce that one zealot like a ping pong ball when told the zealot stole from him - that's trauma rage babey!!! And how secretive he is about projects. Getting talked down to about projects when nuerodivergent Hurts when it clicks. And the RSD. He wants to be respected and being insulted really hurts!