The Cradle of Olympus

Taking place for a brief period in Ancient Greece, at a time when the Olympian council of Gods haven't reached their full potential yet, an unknown entity has emerged that has even the Fates agitated. What could it possibly be, and what is it's connection to Olympus as a whole. (M rating may be temporary, changed for mention of r*pe and not sure if change needed. Happens in ch40)