Not to step on any toes, but ive read several posts about Demons, as if they are a bad thing, a true Demon is a Divine Being, a true Demon, (is capable) but will rarely attack or possess a human being. in the rare instance of actual spiritual possession, the Demon was invited to do so or they saw no other alternative.
Negative entities on the other hand, don't care, and can often make one believe it is a Demonic possession.
I have a Demonic Guardian, he would never hurt me or my loved ones, he has helped me over the years more times than I can count. They are teachers, protectors, and allies.
So if your really interested in Demon's do some research, they are not what the neo-pagan and Christian traditions say they are.