plural stuff, FFX spoilers
Tidus from Final Fantasy X is actually fairly relatable as a member of a multiple system. Partway through the story he learns that he doesn't exist in the way others tend to define "exist", but... he's able to take it in stride, because in every way that really matters he does exist.
re: plural stuff, thinking about video games
I wonder if an unconscious understanding that we're plural is why we liked Baten Kaitos so much? In it, you play as the guardian spirit of the main character Kalas; essentially his headmate.