Demonic sneer. Grandiose look on face. Attitude of one up, I've got you.
Only admire character traits that are useful for manipulating others.
Will give you bad information and they deny ever giving it.
Change moods in a flash without any recognition of prior mood. Can rage for 20 minutes, leave room and come back within seconds with a totally different energy. They have no idea what came over them. Won't even remember it.
They lose it. Eyes go black with rage, can be over nothing--the jar wasn't closed.
Rictus grin - wide, fixed grin that doesn't go to eyes. Imitation of what they imagine to be joy, but isn't.
Vacant stare even right at you till you look away.
Change identity to suit situations. Change the form they appear in to match the next person they want to manipulate and destroy.
They consult the occult.
Use your beliefs against you, usually out of context, including manipulating you to not divorce them. [However, God does not want you to stay with a demonic monster. "Don't be fooled by a twisted tongue."]