There must be areas in which a particular character does not represent you.
We live in a sea of general ideas, so that's not a novel, since there are so many general ideas. But the moment a particular idea is linked to a character, it's like an engine moves it. Then you have a novel underway.
Once a novel gets going and I know it is viable, I don't then worry about plot or themes. These things will come in almost automatically because the characters are now pulling the story.
Actually, I identify with all my characters, good and bad. I have to do that in order to make them genuine. I have to understand them even if I don't approve of them. Not completely - it's impossible; complete identification is, in fact, not desirable.
