Teenagers are famously difficult to please and yours are no exception. "The Heroes of Olympus" series of young-adult fiction novels are perfect for picky kids because they help make reading fun. The best-selling series features the adventures of a band of young heroes who unite to stop the nefarious schemes of Gaea, an embittered demigod who plans to destroy the earth. The series, written by the American author Rick Riordan, consists of five books. "The Heroes of Olympus" saga is educational too because it features many references to ancient history, taking the time to name and explain many of the gods and goddesses from the ancient pantheons of Greece and Rome. No matter what titles in the Heroes of Olympus series you are looking for, from the first book, "The Lost Hero," to the last book, "Blood of Olympus," you are sure to find a huge range of novels perfect for adults and kids alike on eBay.