Plurality
From Tymestl Wiki
Plurality is simply the situation of multiple individuals sharing one body, nothing more or less than that. Sometimes it becomes disordered, most of the time it is not, or only very minorly so.
We will flesh this page out more in the future, but for now I'll leave a link here to the best resource on the subject I know. Astraea's Web
MPD Comic - Here's a little comic about it, to make it easier to understand. :)
