Firebrand - Firebrand Trilogy, #1

Carlan Andrassis is a Firebrand, one who can create and control fire, as well as a Lord of the second most powerful House in the Ten Kingdoms. He is also a young man with a dark secret that makes him afraid to use his power. But as a terrible plot plays out around him, he must learn to conquer that fear, or be destroyed by it. Jada Suvari is a Firebrand as well, and daughter of the High King of the unified kingdoms of Garden.
A spoiled, willful young woman with a quick temper, her world revolves around herself and her whims. But when a little harmless flirting with a handsome young knight leads to danger, Jada finds herself forced to face a truth inside her own heart.