Those movies about Dissociative identity disorder that you've seen are typically over reacting or are actually psychopathics. But the reality is people with DID are typically normal everyday people living with the struggle of every day life. There often harmless, but have their own battles just like any other human being. It's also a myth that it's rare or only happen when you have black outs its different with every person so to compare people to each other wouldn't be a good idea. Last i checked though i'm not a evil person and i never harmed anyone also, unless i told someone you'd never know actually nobody would know. And no, my personality's don't wish to harm others in fact they're here to protect me and that's it. Dissociative identity disorder typically happens when someone has been abused as child or adult or someone has experienced traumatic events.