I've sort of prided myself on playing characters with conscience. The first way I go about creating a character is looking at that area of conscience. What have they done, and what has it cost.
When you're playing a real character, you want to honor that person and receive inspiration from that person. They need to anoint you in some way that allows you to borrow just a small piece of their soul. That is the flame.
You can't play history and you can't play historical characters. You just have to reduce it to the ordinary.
I love characters that are very layered and complex. It's more exciting and different than any simple role- plus, I love a good challenge.
As an actor, I usually have to find something to love about my character in order to play her.