In "The Titan's Curse", Nico is a composed kid who loves a trading card game called Mythomagic. However, since his sister's death in "The Titan's Curse" at the hands of a defective Talos, he has a hateful resentment toward Percy. He later thinks Mythomagic is a stupid game, and burns all his cards in a fire. He becomes more sullen and solitary, saying that "only the dead respect him... and only out of fear". He believes that he will never be accepted with the living, but forgives Percy after Bianca tells him that it wasn't Percy's fault that she died. He also accepts the small figurine of Hades that Bianca wanted him to have before she died in "The Titan's Curse". In the fifth book, he brings Percy to his father to get information that proves to be the least his father can give, and his father ends up putting Percy in a dungeon. However, Nico rescues Percy from the dungeon and takes him to the River Styx where Percy becomes almost invincible. In the end of "The Last Olympian", Nico convinces his father, Hades, to help the other gods fight in the war against the Lord of Time, Kronos, and his army, and plays a major role in the victory. The relationship between Percy and Nico becomes close for they both might have been the child of the Great Prophecy.