Schizophrenia is often used to characterize what people often describe as having "Multiple Personalities." Instead, it is called, dissociative identity disorder. A condition in which at a young age, an individual suffered trauma so extreme that they had to create an imaginary persona to be able to pretend it was someone else being hurt. This is how they protect their "main" ego. Due to this trauma being ongoing and not being resolved, the defense mechanism gets left on, and at moments of high stress response, the personality automatically kicks into play as a defensive mechanism designed to handle cognitive overload/stress.