Dragon's Tempest (The Imperial Series) - Imperial, #2

For a hundred years, dragons and wyverns have been at war. The wyverns, confident that any real threats have been destroyed, rule the Wastes as tyrants, using the blood of the locals to fuel their dark magicks. For a hundred years, the wyverns and their Riders have remain unchallenged. Tired of living in his father's shadow, Tristan flees the Empire, looking for adventure, excitement, and a chance to prove himself.
Sailing south into the unknown Wastes, he hopes only to make his father proud. Instead, he finds himself thrust into the middle of a war he could never have imagined. With few allies and even fewer friends, Tristan must battle against the forces of the Dark, hoping that instinct and courage alone will be enough to ensure victory.