I've thrown this question out before, but there's always room for new thought on it:
How do you, personally, *make* characters?
Do you design them to interact with each other? Do you flesh out their backstory before you start writing? Do you discover them as you go? Do you decide on race, gender, religion, sexuality, and all that ahead of time? Do you divide them between heroes and villains? Do you "see" and "hear" them in your head?