Nico Di Angelo[edit]
Nico di Angelo is first seen in The Titan's Curse, when several other characters come to his boarding school to bring him and his sister, Bianca di Angelo, to camp. At the end of The Titan's Curse, it is revealed that Nico is the son of Hades. Though he appears to be ten years old and therefore a violation of the "Big Three Oath", it is later discovered that he and his sister were born in the 1940s; and, after having their memories wiped, stayed in the Lotus Hotel and Casino until the present day.[8] He undertakes a quest to discover his history, and learns that his mother was Maria di Angelo, the daughter of an Italian diplomat.
Nico is initially depicted as cheerful and childish, and described as olive skined and dark-haired. He enjoys playing Mythomagic (a Greek-mythology-themed card game similar to Magic: The Gathering) and can quote the fictional statistics of gods and monsters from memory. After Nico learns of Bianca's death in The Titan's Curse, he becomes moody and secretive. From this point on, he is usually described as pale and shaggy-haired, always wearing dark clothing. Nico, despite being an extremely powerful demigod, is depicted also as extremely lonely due to his frightening powers and family reputation, much like Hades himself. He makes many other characters uncomfortable, in part due to his powers over the dead and his unnerving weapon of choice: a sword made of iron cooled in the Styx called Stygian Iron capable of absorbing monsters' essences, rather than simply banishing them to Tartarus.
Nico initially blames Percy for the death of his sister Bianca. In The Battle of the Labyrinth, Nico contacts Bianca's ghost and, after learning that holding grudges is a fatal flaw for Hades's children, he lets go of his hatred. From this point on until meeting Cupid in The House of Hades, Nico struggles with an attraction to Percy, developed when Percy first protected him from Dr. Thorn in 'The Titan's Curse', which he considers embarrassing and tries to hide. At the end of The Blood of Olympus, it is implied that he begins a relationship with Will Solace, son of Apollo.
Nico is important to the plots of both Percy Jackson & the Olympians and The Heroes of Olympus. Percy makes it his goal to find Nico in The Battle of the Labyrinth, and later undertakes a small quest with the son of Hades in The Last Olympian. In addition, Nico was privy to the fact that there were two camps, one Greek and one Roman, before The Lost Hero, which makes him an important liaison between the two groups during the Heroes of Olympus series. The seven demigod protagonists of the second series also undertake a quest to save him when he is captured by Gaea's forces. Lastly, Nico brought Hazel Levesque, daughter of Pluto and his half-sister, back from the dead and helps her control her dangerous powers.