List of Percy Jackson and the Olympians characters
Luke Castellan: One of Hermes's children and a major antagonist of the series. Though initially the counselor of Cabin 11 and an ally to Percy, he revealed his true nature as a high-ranking member of Kronos's army by attempting to kill Percy at the end of The Lightning Thief, and on several occasions afterwards. He is shown to harbor a great bitterness towards the gods (particularly his father, Hermes) for what he regards as abandonment. His mom is driven crazy because she tried to become the Oracle. After reforming, Kronos took Luke's body as his own but when he saw Annabeth and the knife he gave her, he remembered his promise to Annabeth that he would never harm her. After Percy made his choice to give Luke the knife, Luke kills himself by stabbing his own Achilles spot to destroy Kronos, fulfill the prophecy, and become the hero of the war. It is unclear but sort of obvious that he likes Annabeth Chase because he tries to save her from being killed by Atlas in The Titan's Curse.