The reason that demi gods, in the Percy Jackson series, are prone to be tested having ADHD is because Rick Riordan son has ADHD. Richard Russell "Rick" Riordan, Jr. (born June 5, 1964) is the author of the Percy Jackson and the Olympians series. Riordan expanded the two series – The Kane Chronicles and The Heroes of Olympus – simultaneously. Rick Riordan is the #1 New York Times bestselling author of the Percy Jackson and the Olympians series, the Kane Chronicles, and the Heroes of Olympus. * He and is wife share a birthday (June 5) and got married on that day. ... Rick Riordan thought in his years of college that he was going to be a rock star and studied guitar and music. He also helped create another Children’s book for children entitled The 39 Clues. Riordan’s Mystery Novel. He is also the younger brother of the late Bianca di Angelo and the paternal half-brother of Hazel Levesque. He is also the author of the multi-award-winning Tres Navarre mystery series for adults. * He met his wife, Becky, when they were just sixteen. Eventually changed his mind and became a teacher. He also wrote the Tres Navarre mystery series for adults and helped to edit Demigods and Monsters, a collection of essays on the topic of his Percy Jackson series. 2. Nico di Angelo is a fourteen-year-old Italian-born Greek demigod, the son of Hades and Maria di Angelo. * His favorite relationship between his characters is Frank and Hazel’s. Take a quiz and test your knowledge of all things Rick Riordan. Five Fun Facts - Rick Riordan. Rick Riordan decided to write a mystery novel which was set in his hometown of San Antonio and was published in 1997.