Nico di Angelo is a son of Hades, Bianca's younger brother and Hazel Levesque half-brother and Percy Jackson and Thalia and Jason Grace's cousin. At first Percy assumed Hades broke the oath not to have children after World War II, but Nico and his sister Bianca had been placed in the Lotus Casino, where 'time stands still' since before the oath was made. At the time, he took great interest in a game called Mythomagic. Nico has the power to raise skeletal warriors, shadow travel, and create great fissures in the ground that swallow up anyone or anything unfortunate enough to be standing on it at the time. For a time, he was Percy's enemy, blaming him for the fact that he had failed to protect Bianca as he had promised, but they became friends eventually. Nico tried multiple times to contact his sister and had difficulty contacting her, even using his dreams. Nico refused to stay at Camp Half-Blood in the fourth book after noting that he was not welcomed at Camp Half-Blood; he compares this to the fact that his father is not welcomed at Olympus. Several months later, he informed Percy of a plan that could lead to defeating Kronos. In the final book of the first series, he convinced Percy to bathe in the River Styx, making him invincible barring the small of his back. In the end of the final book Percy makes all the gods and goddess to 'claim' all their children and make sure they have cabin's in Camp Half-blood. Nico goes back to the camp and makes a cabin for himself and all the other minor gods and goddess. Later in the Heroes of Olympus series,he became captured by to giants [in mark of Athena] though he survived. Through out house of Hades and at the end of blood of Olympus,it is said that Nico has a crush on Percy,though he gives up that dream and goes to Will Solace,the son of Apollo,and in trials of Apollo they are seen as a couple.