Having a dark past that keeps popping up is an intriguing backstory for a player character. Perhaps they're trying to get over it, put it behind them, but occasionally they'll come across someone who knows what they've done, and sees them in a completely different way to everyone else.

Transcript

Luke: I know there was never any good in my father, but there's still good in you.
Darth Vader: No. You're wrong, Luke.
Luke: Obi-Wan told me you were a good person. He said you sacrificed yourself trying to save Anakin.
Luke: I cherished your memory. I loved you. A woman - my mother - who was trying to do the right thing. And I still think that's you.
Darth Vader: I blew up my own homeworld. My family. Jar Jar Binks. That's not something you just move on from.
Luke: The rest of your life depends only on what you do from now on.
Luke: I won't turn to the Dark Side.
Darth Vader: I see. So you won't join me. Why shouldn't I cut you down where you stand?
[SFX]: Whooom! {turns on Luke's sword}
[SFX]: whmmmm...
Luke: Nice try, mum. And maybe you'll stop this moon and turn it around if I don't start behaving.