Well I can feel sorry for anyone if I can devle so far back that you can see what went wrong or what was the cause of them being the less likeable person that they are now. Thing is though, these people are all adults now, and while their past might inform and make them the way they are now (which I won't deny is possible and to an extent deserves some sympathy), they still are the ones with the power to change and become better. Lots of us have crap beginings, some will be far worse off than the likes of say Heavy, Bear etc, and yet they can take the pain, their anger all the things they felt were unfair to them and show they're still the bigger ones despite that.
Heavy, at least now from what it looks like on live feed, has seen some light, and is not going to be like the gang anymore, or squad. The silly thing about the squad is they're not even a squad, they're just with each other as a group in shallow terms, as most of them would do a lot better by not being around each other and mimmicking behaviour to fit in. They're all quite insecure to that extent, as they feel validated in the group rather than just be being their own selves. Heavy D was always goijg to be the butt of jokes in that group, and while the other people in that house don't particuallry like Heavy any more, they at least prob won't pretend they like him to the extent the others do. They'd more talk to him but not play some 'we're you're mates that's why we laught at you' type routine. The likes of Sira, Sam, James, Biggins will talk to him, not iscolate him, but not pretend to be his mate while clearly laughing at him.
I fon't feel sorry for him myself, but I don't think he needs pity, he just needs to grow up, wake up and learn that personal insecurities and they way you've been trreated in the past don't have to manifest negatively on you if you try hard enough. That's not to say life can become perfect if you try, but you'll prob reach a level of feeling better if you do rather than if don't bother at all.