The Halfblood King: Book 1 of the Chronicles of Aertu

Aleron's world turns upside down during a journey to the capital, when a mishap reveals that the simple country boy is a halfblood, heir to the thousand year vacant throne of Sudea and his grandfather is really a nine thousand year old elvish sorcerer from legend. Likely a sorcerer himself, though not yet of age, Aleron must reconcile himself with a destiny he never wanted, but was ordained of millennia-old prophecy.