Luke Castellan is the Greek demigod son of Hermes , the Greek form of Mercury. Before The Heroes of Olympus series he was one of the enemies of Percy Jackson. Luke He the Olympian gods until Annabeth Chase pleaded for him to come back to her. He was mentioned briefly in The House of Hades when Annabeth was at the edge of one of the rivers in Tartarus. The murdered souls kept telling her it was her fault that Luke had died, that there should have been another way to save Olympus and him.
In the film Lightning thief he was portrayed by Jake Abel and film adoption sea of monsters he was portrayed by Jake Abel again