The Head, the Heart, and the Heir series books:

Warren lost its princess once before, and now, in exchange for the lives of those she loves, Princess Alex has surrendered her freedom again. As long as Alex remains at her uncle Moorloc’s castle, Aaron will be safe—but the same can’t be said of her. Desperately trying to learn control of the magic coursing through her, she is now a prisoner trapped by cruel men who despise her for being both powerful and a woman.

Determined to rescue Alex, Aaron takes up his mantle as Datten’s prince and declares war on Moorloc, leading a cavalry of the best knights from both kingdoms into the Ogre Mountains. But the location of Moorloc’s castle is a mystery, and he is forced to seek an audience with the King of Betruger, an old enemy more likely to imprison or kill Aaron than help him.

As Alex and Aaron fight their way back to each other, they discover new allies and confront new foes. To be reunited, they must push beyond their limits and step into their destinies. But will they survive their own battles? And if they do, will they ever be the same again?

Note: This book deals with mature content and is recommended for upper YA (15 +)