User blog comment:FairyRaven/Fairy Tail Chapters 338, 339, 340: Review and Commentary/@comment-4829046-20130705123559/@comment-4829046-20130706023114

-_- A para from answers.

"Moving on to the word demon. The word demon, which is used for a number of different religions in translation, comes from the Old Greek daio, which means "to separate." This term referred to beings in the pagan myths who were higher than men, but lower than the gods. The word eventually morphed into the more familiar daemon or daemones, which then changes to demons. So from this we can construe that demons are less powerful than devils, and if we look a bit closer, we can also guess that they're formed from the breeding of the divine with the mortal.

There is a phrase in Genesis that refers to the sons of God coming to the daughters of Man. Without out and out saying it, it's referring to the breeding of angels (or devils in this case, since it's assumed the act is below angels still in heaven) with mortals to form "giants." Examples of this sort of breeding can be seen in a variety of forms, such as Lilith breeding with mortals and with spirits to create her offspring. Succubi and incubi are creatures of spirit that come to sleeping mortals and have sex with them; with the succubus creating evil spirits and the incubus impregnating women to create half breed children called cambions. An old Celtic myth claims that Merlin might have been a cambion."