Varimar by L.P. Peace

For the crime committed against their people, the Klevian warriors seek revenge against Earth! Yet when a human is thrown into Varimar’s cell, he discovers he wants more than simple contrition; he wants her very soul!
Cara is the only survivor of an attack on her ship by a group of mysterious aliens. When she’s thrown into a cell, at the mercy of a Klevian warrior, a species Earth has been at war with for thirty years, she fears the only way out for her is death.
Captured by the Faradne and locked away in a dark distant cell, Varimar fully expected to die alone. Yet when his enemy is thrown in with him, he sees an opportunity to seize revenge before his end.
But when he touches the tiny human, everything changes. Varimar finds himself desperate to free her and warn both their worlds of an even more significant threat.