God of wisdom. Invented writing. Appears as an old man calling himself Hermes.
No one remembers his birth, but he is quite possible a son of Ra. Was chief diplomat and mediator between the Egyptian pantheon and the Mesopotamian one, at least until the former massacred the latter.
Perhaps in a delayed reaction to said massacre he left Egypt and traveled the Mediterranean, eventually finding a spot as Hermes in the new Greek pantheon of Zeus. He spent many centuries on Olympus and seemed to be pretty happy with it, until Apollo's betrayal and the subsequent bloodshed.
Since Apollo killed Zeus, he stayed underground, planing his revenge. It's taking him long, but he is an old God, and time is different for him. It is highly probable that the PCs are his unwitting agents.