Amy: I don't know why I'm telling you this. After all, I am a demon. Anyways, demons are probably the hardest thing to identify. They possess bodies mainly, but their natural form is a black cloud...Err, we're a little self-conscious about black clouds. In demon talk, that counts as walking around in public without clothing.
Anyways, there are a few ways you can identify a demon. One, they can appear very suddenly behind you and act like they were there all along.
Two, they're eyes become black, or in the case of some demons, yellow.
Finally, if you know a person and they start acting strangely, that's probably possession.
How do you get rid of a demon? That is for me to know and for you to find out...unless you're a demon hunter.