Legend of the White Dragon: Fireblood

One of the five-book Legend of the White Dragon epic fantasy series.

A legend exists among the tribes of the Caveshi Plains, a legend of horses blessed by the Creators for their service in a war against a terrible Darkness. Thousands of years later, the servants of Darkness have returned and prepare to reawaken their master. The horses remain in hiding, except for one.

Alo is a special stallion and his rider, Ayali, knows it; but when Alo insists on rescuing a strange man fallen in a dragon attack, no one understands the horse's purpose. Ayali's only clue is the magic she feels within the man. Over time, her abilities have weakened. Without magic, she cannot fulfill the expectations of her family and her tribe in becoming the next priestess. Ayali desires to gain that knowledge from the stranger, but with his memories gone, he can tell her nothing.
To fulfill her destiny, Ayali must face a growing darkness within her before it consumes their world and destroys her life. Alo may hold the key to her redemption but will he reveal his secrets before it's too late?