The Secret King. C.J. Miller

A princess in peril must choose between duty and desire in this electrifying romance No one believes Princess Serena has the strength to rule Acacia…least of all Serena. But the assassins that placed her in line for the throne have turned their sights on her. And the mysterious Casimir Cullen–who's already saved her life once–is the only man she trusts. Serena is drawn to Casimir with overwhelming ferocity. But affairs of state require that she marry King Warrington of Rizari.Casimir's relationship with Serena was supposed to be a means toward revenge against Warrington. Falling in love was never part of the plan. Now, protecting Serena and bolstering her self-confidence has become his priority. But what will happen when she learns his secret destiny?