Luke Castellan is 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 afterward. He is shown to harbor a great bitterness towards the gods (particularly his father, Hermes) for what he regards as abandonment. His mother had been driven crazy upon attempting to become the Oracle, leading to a stressful childhood. After reforming, Kronos does not need Luke's assistance. However, in his duel with Percy on Mount Olympus, striking Annabeth reminds him of his promise to protect her. This temporarily frees him from Kronos's influence. Percy makes his choice to give Luke Annabeth's knife, and Luke, cursed by the broken promise, kills himself by stabbing his own Achilles heel to destroy Kronos. This fulfills the prophecy, with Luke being the foretold hero. In the film, Luke is portrayed by Jake Abel.