In the Shadow of the Dragon King (Chronicles of Fallhallow)

Seventeen-year-old Eric is a kick-butt squire to the most revered and protective knight in Fallhollow--well, he would be if Sir Trogsdill allowed him to do anything even remotely chivalrous. Determined to prove his self-worth, Eric sets out to find the mythical paladin summoned to protect the realm. After all, if he can join forces with this legendary savior, Sir Trogsdill will have to promote him to knighthood, right? Meanwhile, 16-year-old David is whisked off to the magical realm of Fallhollow where everyone thinks he's some sort of paladin destined to fulfill a wacked-out, 200-year-old prophecy. As paladin, David is supposed to help kill a dragon bent on destroying the realm, but he needs some sort of magic key to do it. The problem is that the key is around the neck of an annoying squire who's too wrapped up in proving himself which makes him completely unhelpful. With egos as big as the dragon they need to destroy, Eric and David must get over themselves or watch everything they know and love burn.