It's hard to know exactly how people develop the characters they do. There could be people from humble beginnings that turn into jerks. Some characteristics are just part of that special soul of that human being.
I look for two things when I am about to launch into a book. First, there has to be a dramatic arc to the story itself that will carry me, and the reader, from beginning to end. Second, the story has to weave through larger themes that can illuminate the world of the subject.
I want my books to last, to stand the test of time, and to do that I focus on the forces that shape the subject - the cultural and sociological geography - to capture them in a way that will explain them no matter what they are doing.
My basic philosophy is that no human being is a saint.
I believe that life is chaotic, a jumble of accidents, ambitions, misconceptions, bold intentions, lazy happenstances, and unintended consequences, yet I also believe that there are connections that illuminate our world, revealing its endless mystery and wonder.