Since The Adventures Of The Roly The Coach kinda shares the same universe as Shed 17, here are some of my headcanons for Roly lol
Headcanon 1: Roly is autistic and non-verbal. (Tbf, most if not all of the characters in Shed 17 can be interpreted as neurodivergent imo. I mean, the reason why people even signed up for biofusion in the first place was because they were railway enthusiasts. Annie and Kevin Diesel literally got married within WEEKS of knowing each other because their shared hyperfixation was that strong).
Headcanon 2: Roly actually likes spending time with Billy and Sarah. In fact, I'd like to think that they have the same taste in music; it's just that Roly simply wants some peace and silence. And who can blame him, really? The guy's been treated like shit by most of the people around him that it feels like a cruel joke.
Roly ilysm <33 He's me if I were an orange coach with a pair of sisters who'd never call
FINALLY, A FELLOW ROLY ENJOYER HIIIIII!!!!!!!!! :D
I always just thought he was mute. I think he also seems to like Bill and Sarah, I don't think he would be hanging out with them if he didn't.