Legion

Brandon Sanderson has had a series of stories featuring a character named Legion (real name, Stephen Leeds) whose “superpower” (in a thinly defined world mostly similar to our own, but with science fiction elements) is a form of multiple personality disorder. In essence, he hears voices and sees things, specifically, other people. These “aspects” encapsulate and represent the information and expertise that his own own mind cannot itself contain and represent. Think of them as a coping mechanism for a supergenius.