Back to the topic at hand.
What about growing up with a deficient character, being unaware of it, then getting hold of immense, terrifying power?
What about being over-intellectual and eventually thinking into a conclusion that turning over to the other side is of greater benefit?
What about a dumb yet lovable character losing their morals in a series of stupid actions and decisions in pursuit of some simple pleasure?
What about someone saintly with a suppressed wilder side who wants to believe in the system being inherently being able to sort out injustices, only to be gravely disillusioned and then realizing how fun it's going to be striking out against the cold, unfair system so deserving of it?
It was chance, fate or whatever you believe in that enabled us to meet.