Just this really.
We had an unofficial class reunion quite recently. There were some really evil bullies in our class, and now they are decent citizens, family people and caring parents, but I looked at them and thought that they just couldn't switch to the good side so easily and fully. How can one be really evil in the school and then suddenly become so very nice and kind and respected, and even doesn't (really?) remember his/her own evil deeds towards others? Do they really forget what they have done to some of their classmates, or they just don't care and think of themselves as good and decent people? Even knowing what they did? Or do they just laugh it off and say "oh, such and such had it coming/was too sensitive for his/her own good"? And everybody just thinks a world of good about them?
I remember my own bully, now a very respected family man. He just sort of laughs everything off. I don't think he's really changed.
Is it possible at all? Can such people change?
I still think that the little shit that once tortured kittens still is the same shit even if all grown up, respected in his job and raising a family.