ben building a profile on negan, can't be sure, but I think it goes something like this;
as a child his father was an abusive ash hole to punish negan he would burn him, with an iron or something like it, the bandage on his wrist is either a scar where he attempted suicide or a place where he was burned after his father covered his back with burn scars, we have yet to see him with his shirt off.
his mother was an enabler, she stood by while his father did what he did to him, she wasn't strong enough to stand up to his father, and he wasn't strong enough to protect himself, and, more than likely, he was forced to fight his father when was old enough to protect himself and his mother, or he was able to protect himself but not his mother and she was killed by his father.
he sees a kinship in Darryl and carl more than likely that is why he hasn't killed them yet, and I think he sees Judith as the child he has yet to have.
I think he sees rick as a surrogate father figure that he gets to torture for revenge.
I guess we will need to wait and see what all happens though, to see if I am right or not.