The Whispering Fang (en Inglés) - Lili K. Buckley

In the aftermath of the battle, Waenia Wyvarian is no longer a princess riding to war. She is its prize.
Taken by Luvian Veskar, the enemy she feared, Waenia is forced into a journey she never chose, one that draws her deeper into the man behind the war. Along the road to his hidden camp, hatred gives way to understanding. Fractured memories begin to stir of another world and another life, where she and Luvian were not enemies but something far more perilous. A past she cannot fully remember, yet cannot escape. Luvian is not what she believed, but neither is he safe.
Behind them, Darrion Rhoane follows her fading trail across the kingdom, racing against shifting armies, false paths, and a growing darkness.
The war changes when the Whispering Fang is found. In the hands of Malvaris Wyvarian, the dagger awakens a power tied to the Lystrians, a force that consumes and commands. As the king weakens and the throne falls under Malvaris's control, Thiros begins to unravel from within. Villages fall silent. The dead do not stay dead. The truth about the Lystrians, their purpose and their hunger, comes to light.
At Luvian's camp, alliances shift and truths surface that shake everything Waenia thought she knew. The past presses closer, revealing a bond neither of them chose to keep, yet neither was able to sever. Luvian struggles against it, torn between what he remembers and what he sees, as she stands beside another. One by one, the heirs of the Nine Kingdoms begin to converge around her in ways long foretold, each bringing their own motivations and secrets that complicate Waenia's journey. But with Malvaris rising and the Fang calling to the dark, Waenia can no longer return home as a daughter.
If she is to save her father and free Thiros from the blood tightening around its crown, she must choose a new path.
One that may cost her everything.