Demons have been a part of human storytelling since the advent of the art.  Described by different cultures as fallen angels, evil spirits, or extradimensional beings from a nightmarish hellscape, all of their disparate descriptions share a common interest in, and hatred of, humanity.  Noted for their interference in human affairs, these hellish creatures can be both violent and seductive.  Demons are renowned for possessing their victims, as well as brokering misleading agreements and corrupting the spirits of hapless humans.  Regardless of your belief system, it's best not to tempt fate when it comes to these demonic ne'er-do-wells.