Bring Me Their Hearts Series

Zera is a Heartless - the immortal, unaging soldier of a witch. Bound to the witch Nightsinger, Zera longs for freedom from the woods in which they hide. With her heart in a jar under Nightsinger's control, she serves the witch unquestioningly. Until Nightsinger asks Zera for a prince's heart in exchange for her own, with one addendum: If she's discovered infiltrating the court, Nightsinger will destroy Zera's heart rather than see her tortured by the witch-hating nobles.   

In order to protect Prince Lucien d'Malvane's heart, Zera had to betray him. Now, he hates the sight of her. Trapped in Cavanos as a prisoner of the king, she awaits the inevitable moment her witch severs their magical connection and finally ends her life. But fate isn't ready to give her up just yet. With freedom coming from the most unlikely of sources, Zera is given a second chance at life as a Heartless. But it comes with a terrible price. As the king mobilizes his army to march against the witches, Zera must tame an elusive and deadly valkerax.

With the rise of Varia d'Malvane comes the fall of the Mist Continent. Cavanos is overrun by the brutal rampage of the valkerax, led by its former crown princess. Vetris is gone. Helkyris is gone. As each mighty nation falls, the grip of the crown princess closes around the throat of the world. But Zera Y'shennria isn't out yet.