Ladysmith's Forge

Apparently, these were some of the most feared creatures in the ancient Celtic world. And if you were REALLY bad, you got turned into one and suffered for all eternity. (I refer you to Aoife, the step-mother in the Celtic Snow White equivalent The Children of Lir) 

Now, the thing is, that story is the only place I can find any substantial reference to demons of air. They are mentioned in the Tain bo Cuilagne (The Cattle Raid of Cooley) but only in passing (the passage in question involved Cuchulain roaring in anger, and the demons of air all fly away in fear. Not exactly helpful.)

Then, I found The Dictionary of Celtic Mythology (Thank you, Google Books! You have once again saved my bacon!) And on page 353, there was this interesting little snippet, that again talks about Aoife: 

Aife then proceeds to Bobd's palace at Killaloc, where her treachery is soon discovered and she is punished by being transformed into a demon (sometimes vulture), condemned to wander through the air forever.

 Now, demon is not a term that is native to the ancient Celts. They borrowed it (or it was applied to their mythology) by later Christians. So what was it that the Christians were editing to suit their own mythos?

 I have my ideas. And they'll show up in Princes of Air. (What, did you think I was going to just tell you?)