Most of my favourite characters have been abused at some point. I have a new one, a werecat called Miles, whose father was cruelly, coldly abusive. Then there's Monty, he's human but he made a deal with the devil to make him immortal. He was abused by his father. Ayla was abused by her masters [she was a slave], Kana was abused by basically everyone she came across because she's half-wyvern, therefore different, therefore... cops crap from everyone [I guess I broke her, kind of, considering she's batcrap crazy and a serial killer now], Elan is Monty's twin sister so same crap with her father as Monty had... and another new one, Ahjeyah was raped.
Then there's the ones who had good parents and/or have never been abused by anybody. Valiant is chimeric, and when he was born, part of him was werewolf... part human. Which basically meant that when he hit puberty and the werewolf part was gearing up to go wolf for the first time, his body tried to rip itself apart. Dunbar lost her father when she was ten and blamed herself [she's dead now, so is Valiant, this world is on its third generation with fourth to come very shortly]. The list goes on!
So basically I put them through hell. Every single one of my favourites gets tortured. All of them.