A Legacy of Duty and Deception (en Inglés) - Kristen Jennings

Secrets are the only way to stay safe.

Esha must keep her true identity a secret or risk the life of the most important person to her. She isn't Feldor's princess like the kingdom of Solven thinks she is. Her goal is simple: broker a marriage between herself and Solven's crown prince to fight a monster and save the kingdom of Feldor. She doesn't have time for love or romance.

But the wrong prince has decided she's the object of his desire. 

Kasteel will never be king. He has never wanted the responsibilities or trappings of the crown-until her. Esha may have been meant for his younger brother, but he'll stop at nothing to have her. Even if it means risking his life. Or revealing a secret he can't afford to get out, a truth that could change everything.   

Kasteel will pledge his hand and sword to Esha's cause: protect the kingdoms against the monstrous netvor. 

Except monsters aren't the only things hiding in the shadows. All secrets must come out. And falling for the wrong brother might be the thing that saves them all.