Barbarian’s Prisoner by Abella Ward

There’s a secret hiding in the dungeon: The hottest alien on the planet has just been locked up… And all you need to do is find the key.
Life isn’t easy on Planet Tirron, especially when the paranoid psychopath of a king happens to be your brother. Luckily for Arana, the new prisoner that her brother has locked up in the dungeons is the most gorgeous guy she’s ever seen.
So when her brother’s paranoia and harsh punishments become unbearable, Arana knows exactly what to do: make a deal with the gorgeous prisoner. If she sets him free, he’ll take her away.

But like most things in life, not all goes according to plan…
And suddenly, Arana’s gone…
Arathor is a trained assassin who fights in the Death Pit during the day and is healed by Arana at night. He knows she’s his mate, but she can never be his. Arana has a gift that she doesn’t know about and that prevents them from ever being together.
But when the King offers Arathor his freedom in return for Arana’s head, Arathor must make a decision.
Will he betray Arana to set himself free?

Will he give up his freedom for the only woman he loves?