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.
Just released, Legion: The Many Lives of Stephen Leeds collects two of those existing novellas with a new third. The author says there aren’t any more coming with this character, and there’s no (admitted) connection to Marvel’s Legion character. I enjoyed the character when he first appeared, and this conclusion to his story is interesting without bringing the series itself to any kind of classic significance.
It is, I think, a thinly veiled examination of the typical authors feelings about having fully realized imaginary characters occupying significant parts of their thoughts and attention, combined with the common situation of needing to research details for a book on a lot of different topics well enough to quickly sound like an expert to a reader.
