This guy had a stroke and woke up a completely different person:
https://www.youtube.com/watch?v=GR_-qg-upJs
He doesn't remember any of his life beforehand and he has different tastes, hobbies, ect.
I was wondering what could cause this and maybe it's a walk-in/soul-exchange?
Post note: I am actually wondering if the stroke killed him and another soul nearby whether planned or not took over instead?