I think the main thing to remember when writing a novel is to stay true to the characters.
I'm constantly trying to mine the DNA of John Constantine and stay true to that character in the comic books.
I just try to be honest and true to the character and play the part.
When you work on a pre-existing character, when you end up getting invited to be part of a legacy character like Superman, I don't feel like it would be true to the character if all I did was go in looking to express my own voice.
You never want to just be outrageous for outrageous' sake 'cause then it doesn't work, and it's not believable. You want to be as true to whatever character you're playing.
I want to be true to the character and maintain some consistency and give the audience what they love while at the same time keeping things fresh and grow the character.
Each character, be it the antagonist or the protagonist, brings with himself his own personality... and I have tried to stay true to each one of them; each is enjoyable in their own way!
I'm pulling out different aspects of my personality in writing each character and, if I'm doing my job well, I'm being true to the situation and true to the character.