[@Quati] I say do whatever feels like it could be fun to play long-term. ;D  Personally, (and just a suggestion) I'd say the witch had a vendetta against a particular person and forced your character to possess that person. Maybe that person was a well-known hero that the witch hated with a passion -- so when the hero started acting strange and eventually was taken to the Stone, the witch had won: the witch had not only destroyed the hero's mind and sentenced them to a slow death, but destroyed the hero's legacy as well.