Are you into Mpreg? If so think of this, roadhog’s belly is just there because he almost constantly pregnant with the litters of the various overwatch alphas. He loves the feeling of being huge and pregnant and loves it even more when his milk spill out over his belly and gets lapped up by some hungry guys.

oohhh shit… ok… ok I’m gonna make it v angsty and non con (+child death tw) because omega!Roadhog does that to me, so beware the following but:

Roadhog has always been fat, whether pregnant or not; it’s just who he is. Still, he probably did have some run-ins with Alpha groups that caught him at his most vulnerable and bred him up. Obviously they weren’t in it for the long haul and just left him to his devices afterwards, and I can’t see Roadhog being super nurturing towards those off-springs, but also the radiation in the Outback would probably kill off a lot of them; so I can see them either being still-born from the get-go; dying shortly after because he has no means of caring for them, or in the instances where he actually is close enough to a functioning city, leaving them at hospitals.

by the time he comes to Overwatch he’s not exactly been pregnant around the clock but… p often. way more often than any other Omega around. 

when they breed him up, he still does not have any nurturing feelings obviously, so they need to keep a close eye on him and how he treats himself. Need to work him up to not just getting his litter in a back alley and leaving them there like he taught himself to do. It’s not like he’s doing it maliciously, per-se, but it’s just how he learned to cope.