At Knudepunkt 2015 I saw a really good talk by Elge Larsson drawing the connection between immersion in larp and possession in shamanistic rituals. Particularly the idea that possession is brought on by repetitive endowment.

The idea of possession is a useful way to understand playing characters. You summon them into your body by repeating certain habits and phrases. You begin with a weird dual conscious of being aware they are making separate decisions. At it’s peak the character completely takes over you and annihilates any separate sense of identity. When the show/larp/ritual is finally over you are left with a weird sense of them departing. With an odd idea that they still exist somewhere else.