On my first Playthrough i thought the oversser must be Zeus or Hermes. However --as Mathmatican-- MC i answered "Athena" being the overseer for roleplay purpose. In most Saga i read (so yes, i am biased) Athena has been very helpful for humanity; Jason and the Argonauts, Odysseus, Thesseus and she propably helped Daidalos to contruct the Labyrinth. My MC assumed that Athena must be plotting against all Olympus to set Humantiy free from the Gods, therefore she set up the trail that Zeus was going against the oath to Styx.