https://www.youtube.com/watch?v=uxktavpRdzU
https://www.wikiwand.com/en/Dissociative_disorder
Dissociative identity disorder – See Serial Experiments Lain, for a good depiction of DID (for e.g. this scence, or another scene where she is trying to strangle evil lain, but they share the same body..
. related to Hypnosis, Schizophrenia: you have thoughts; but who is the author of those thoughts? You can have a disordered sense of self.