Nico di Angelo is a fictional character in Rick Riordan's Percy Jackson and the Olympians series.Nico di Angelo is Bianca's younger brother, the only known son of Hades. At first Percy assumed Hades broke his agreement with Zeus and Poseidon to not father any lebih children after World War II, but Nico and Bianca were born before the pact was made, and had been placed in the Lotus Hotel and Casino in Las Vegas, Nevada, a casino that prevents its occupants from aging. This part of Nico and Bianca's background is first hinted at during The Titan's Curse when the gang is forced to enter the Washington Metro to escape a pursuing helicopter. Nico and Bianca both seem to think that the Metro is very new, as it wasn't there "the last time" they went through Washington D.C. - a statement that at first seems ususual, telah diberi that they are described as being in their teens, and the first segments of the Washington Metro opened in 1976, well before they would have been born.

Perseus "Percy" Jackson is a fictional character in Rick Riordan's Camp Half-Blood book series, appearing as the tajuk character and narrator in the first series, Percy Jackson & the Olympians, and a major character in the saat series, The Heroes of Olympus. At the start of the first series, Percy is introduced as a troubled twelve-year-old diagnosed with both ADHD and dyslexia. After getting attacked at school, he is escorted to Camp Half-Blood, a secret camp built to train and protect Greek demigods. At camp, Percy learns that his father is Poseidon, the god of the sea, and is thus a child mentioned in the Great Prophecy, a prophecy that was telah diberi sejak the Oracle seventy years ago. Throughout the series, Percy embarks on several quests to save his Friends and the Olympian gods of Mount Olympus.