Taking Vengeance by Cynthia Sax

The only force stronger than their hate is their love.

Vengeance hates all humans. They killed every being he ever cared about. When the huge C Model cyborg is told he’s genetically compatible with the enemy, he makes it his mission to capture the female and use her to expel all humans from his home planet. That should be disappointingly easy. She’s a weak, fragile human.
Then she blows up his ship, blasting to bits his preconceived notions about the enemy.

Astrid, aka the Buoir Berserker, hates all cyborgs. They killed her entire clan, including her baby sister. The warrior female has vowed to hunt down and destroy the enemy. When a savage cyborg arrogantly puts his hard, sexy body within her reach, she does the only thing a female can do—she peppers his muscular physique with projectiles.

The more passionately they fight, the stronger their attraction becomes. Neither of them will relent on their missions, yet they can’t keep their hands off each other. Their battle will either end in love to last an eternity or in death.