Underground, by Murakami, was one of the better books I've read. It mostly covers victims, but the later chapters are interviews with various members of the Aum

Underground, by Murakami, was one of the better books I've read. It mostly covers victims, but the later chapters are interviews with various members of the Aum cult. It does a pretty decent job of presenting the psyche of the type of person who joins, stays, and some that leave. Although mostly relevant for what he calls the "Japanese psyche" I still found it very insightful.