The Beginning

Percy Jackson is The Overlord, he was 'born' in a void of darkness, he was there before the Gods, Titans, Giants, Permoridials, Chaos, and Chaos's father, The Void.
He watched everything from the beginning of the universe to the Greek Gods battling the Giants the second time, he never interfered, only watched.
Until he saw the Gods became too arrogant and prideful for there own good.