What is the difference between fictive and “id”? Is there even one?

Good question!

To start with, a fictive is specifically a headmate or alter. They are a member of a multiple collective or system.

As for people who use the term ‘ID’ I’ve been seeing that term pop up here and there along with “literally me”. I am not entirely sure what it means. In context it appears to mean specifically, aside from to differentiate itself from fictionkin somehow. My hunch is that it is mentally ill people stressing that they believe themselves to literally be a character here and now on earth with no other identity. 

If anyone has any more info on what it means to “ID” as a character or the term “literally me” I’d appreciate the heads up.