The devil represent temptation, but it is not evil. Personally , i think there is no such thing as fallen angel, because it is the god's perpose to create the angel that temp human, so that human may over come the temptation, hence move into higher understanding of life. The more ones is free from the temptation, the more happiness ones shall get. In my opinion, this is the god intend. In the Tarot, The Devil serve the same purposes. i draw Pan as the devil in my tarot deck, because this card is rule by Capicorn, and Pan is a wild and reckless god which is connected to tempatation.