Re: What villains should be sympathetic?
I'm only doing the villains I'd care to see:
Riddler (tragic backstory)
This is for the last son, breaking the law shouldn't mean you aren't sympathetic to the characters, Bruce Wayne breaks the law every time he puts on his cape and cowl. These people are all villains and that is why they break the law, however, people like Edward Nygma were emotionally crippled by their parents, Jonathan Crane by school bullies, Harvey Dent and Victor Fries by loss, and Jason Todd by abandonment. These are people who have suffered things that we can relate to and are seen as redeemable.
However, people like Thomas Elliot murdered because he just wanted stuff, Joker does it because it is funny, and Simon Hurt dedicates his life to the corruption of virtue. They are evil so they can perform more acts of evil and are seen as irredeemable.