Possession

I found this on the net thought it might help:

Possession

There are two types of possession; that of a place (usually a house), and the other is in which a person is actually possessed. Both types seem to progress in a similar way. First, there is a time when the demon(s) (or entity) enters the place or person. There are many reasons that can cause the initial entry. The most usual cause activities carried out in the building, or by a person, that is attractive to a demon. Something as innocent as a passing interest in the occult can spark an entry, such as conducting a séance or using a ouija board (both of these mentioned can be dangerous. PLEASE be cautious). Practicing rituals from ancient texts, such as the necronomicon, is asking for trouble. If it ''works'' you just may get way more than you bargained for. Other causes for entry can be domestic violence and abuse, tragedy, and perverse inferences. Once a demon enters a building, it might stay there for a number of years. After it has made it's claim, the demon makes it's presence known to the occupants and begins the process of breaking down the resistance of the afflicted.

This is done in many ways. Whether it be pounding in the walls, stench, apparitions all these manifestations are meant to cause fear and weakness. The assault will continue until the entity has established complete control and dominance. Once this has been done, the family members are terrified, their emotional recourses drained. They turn against each other, and are isolated and alone. At this point they voluntarily submit to the evil force of darkness that has claimed them.