Disassociative Disorders

In class we discussed dissociative disorders and the one i find most interesting is Dissociative Identity Disorder (DID) DID is a disorder where a person takes on multiple personalities and each of these are distinct from the other. These personalities have different skills, they have different writing styles, they may even have different accents. This to me sounds like something that is completely impossible but it is true. I have seen this disorder a few times in movies and things of that nature and it always is shown to be something terrifying or dangerous where in real life this may not be the case.