well, a some people believe that there are fallen angels, like satan.
and then there are demons or unclean spirits... but there not the same thing. according to some people.
some people believe they are two diffrent kind of beings.
because if you look up the greek/hebrew word for angels, and the word for demon or unclean spirits, they are not the same greek/hebrew word.
this causes some people to think they arent the same thing, so intialy, satan is an angel, not a demon or unclean spirit.
thats what some people believe anyway. where do demons come from? uhh i dont know. some people believe they are souls of the dead people that walked the earth and joined lucifer on his crusade agaisnt God, before the time of adam and eve and the 6 days of re-creation.
thats another idea that some people believe, based on a few diffrent scriptures and themes from the bible.
i believe i have encountered demons or unclean spirits, and i believe i have had Gods angels look out for me more than once.