Demons are supernatural beings. Demons exist, both in the physical and spiritual world. They are arranged into hierarchies according to their degree of power. Among all the various levels, from courtier to archduke, there are good demons and bad demons, also known as eudemons and cacodemons respectively. Eudemons are demons who don’t actively seek to screw up the human world. more accurate description would be chaotic and non-chaotic demons. ‘Chaotic’ demons or cacodemons are almost exclusively the kind who come into contact with the rest of us. A sorcerer or witch could summon a eudemon. Even if one said he was a eudemon, he’d probably be lying. A wise spellcaster abjures conjuring altogether.
Demons were first mentioned in Stolen, after Elena 's discovery of supernaturals such as half-demons. All that was said was that demons sometimes take the form of human males and mate with females to create half-demons. The first Demon wasn't seen until Dime Store Magic, when Savannah unknowingly conjured one up in her attempt to summon her mother. The Demon, Paige suspected, was very powerful in the hierarchy.