The Titan's Curse
Nico di Angelo: Nico is the ten-year-old demigod son of Hades. He and his sister, Bianca di Angelo, were trapped in the Lotus Hotel, where time is slowed down. When the book begins, they have been released and are attending a school. They are rescued from a Manticore by Percy, Annabeth, Thalia, and Grover. He is left at camp during the quest, but stays in the Hermes Cabin because his parentage has not been discovered. He leaves camp after hearing Percy broke his promise of letting Bianca die. Before he leaves, he sends an army of skeletal warriors into the underworld. This shows that he is the son of Hades.