Well, In my opinion i think demons are spirits that have never lived on earth or had an physical form. I also believe that they work for "satan/lucifer" If you study and practise demonology you will know what i am talking about.
People think that demons are bad. but infact they are not bad and they are not good. well really it depends on the demon you are dealing with.
For me i truely think that demons trick us, and tell us lies. but thats beacause they was made to do that.
Well like i said this is all my opinion please share your opinions id love to hear them.