Rick Riordan's first Percy Jackson novel, "The Lightning Thief," was first published in 2005, riding on a wave of ultra-popular young adult fantasy literature that persists to this day. One can easily see that the "Percy Jackson & the Olympians" books lift a lot of ideas from J.K. Rowling's blockbuster Harry Potter novels and follow a lot of the same story beats. Both were about young men who, while living unhappy lives among the hoi polloi, discover they actually possess royal blood. Their previously unknown lineages allow them access to worlds of magic and/or deities, which they are able to explore through either a wizards' boarding school (in Harry Potter) or a demigod summer camp (in Percy Jackson).

Both Potter and Jackson also have to face off against intergenerational enemies that are directly linked to their absent parents; with Potter, it was a wizard named Voldemort, and with Jackson,...