Nico is one of the novel’s two protagonists. While The Sun and the Star successfully stands alone, the story is richer if the reader knows Nico’s history within the Camp Half-Blood Chronicles. Nico is the demigod son of Hades and his human mother, Maria. Nico and his sister Bianca were born in Italy in the 1930s and moved to the United States with their mother before World War II. While in Washington, DC, Zeus killed Maria, but Hades managed to save Bianca and Nico and placed them in the Lotus Hotel and Casino, where time moves differently. They spent a couple months in the hotel, which translated to 70 years in the real world, emerging in the 21st century. At Camp Half-Blood, Nico avoided other campers and isolated himself. His sister Bianca became a Hunter of Artemis and died during the events of The Titan’s Curse. She was reborn with their mother in Elysium, an afterlife paradise for heroes and people who lived good lives.

Hades, Nico’s father, is the Greek god of the Underworld. Nico’s demigod powers are inspired by Hades’ powers and are all related to death and darkness in some way. Nico is a necromancer: He can feel the skeletons of dead people and animals inside the earth and raise them to take a form he desires, like the bone ramp that saves him and Will as they fall into Tartarus.