Demon
From Iron Chariots Wiki
Demons, in Christian mythology, are the counterparts ofangels. They are angels which have fallen from grace along with Satan. Demons are inherently evil and frequently plague humanity under the command of the devil.
Demonic Posession
Demons are supposedly able to enter and take control of a human, this is called posession. The Catholic Church uses the ritual of exorcism to expell demons from the victims they posess.
Demon posession is also a historic explanation for those who suffer from neurological disorders such as epilepsy.