People are fascinated by evil because it's mysterious and it doesn't seem to have a rationale behind it, and the second you say that Hannibal Lector was abducted as a child and he had to eat his sister or something like that, it becomes immediately mundane. The character becomes mundane.
“I was a girl from Massapequa, New York. I grew up in Massapequa. I lived in a basement with one window.”