Tairen Soul, book 4: Queen of Song and SoulsC. L. Wilson2009

Two lovers, two hearts, one soul.
Only joined can they be truly complete.
Only joined can they survive the darkness.

The Fey King Rain and his truemate Ellysetta share a passionate love unrivaled in the history of their world—and a forbidden power that made them outcasts from the Fading Lands. As war looms and the evil mages of Eld threaten to rip their world asunder, they must fight to defend the very kingdom and people who reviled them.

Only by trusting completely in their love—and in themselves—can Rain and Ellysetta hope to defeat the gathering forces of Darkness. But it will take more than the strength of their devotion to endure. They must unlock the secrets of the past and find the courage to embrace the dangerous destiny that awaits them. Only they can save their world, but that victory might cost them their lives.