“The Host” (post 3) by Stephenie Meyer (post 4): Belief in Spirit Possession as a possible reason for not seeing Two Personalities as Multiple Personality.

I am half way through this 600-page novel. The protagonist still has her two personalities, Wanda and Melanie. Other characters have come to recognize that she has these two personalities. Yet nobody has called it “multiple personality” or even commented in passing that it is like multiple personality. Why?

My guess is that the author’s religious background inclines her to interpret alternate personalities as spirit possession. After all, what are muses and characters that talk to you in your head but advisory and storytelling spirits? And what is the process of writing at its most intense but a creative form of spirit possession?

Multiple personality is a psychological interpretation of what, through most of history, has been thought of as spirit (good) or demon (bad) possession.

Here is a case from the sixteenth century:
http://www.astraeasweb.net/plural/jeanne_fery.pdf