The Griffin's Boy — Julia Hughes

In an alternative universe Britain remains an island of mists, populated by Celtic tribes and governed by feudal hierarchy. Evolution has taken a different path and mythical beasts exist. Only noblemen's sons are recruited into an elite troop known as the Griffin Riders. The best a nameless nobody like Neb can hope for is to become the equivalent of a stable lad. But then his fate becomes entwined with the mischievous grey griffin Balkind, who everyone knows is trouble…and sure enough, Balkind disgraces himself on recruitment day and is rejected by Griffin Master Romulus. However, Neb is determined to change Romulus' mind. Telling himself and anyone who will listen that Balkind deserves a second chance, Neb steals the beast and flies off on the adventure of a lifetime.