Most hatred is based on fear, one way or another.
Never interrupt when you're winning.
...you don't need ghosts to be haunted. Memory does that just fine without any supernatural help at all.
The only good enemy is a dead enemy.
Love sucks. Sometimes it feels good. Sometimes it's just another way to bleed.
My characters surprise me constantly. My characters are like my friends - I can give them advice, but they don't have to take it. If your characters are real, then they surprise you, just like real people