Coldhearted Guardian by Juno Wells

Hunted by forces she can’t fight alone, her only salvation is in the arms of an alien assassin.

Alexis has spent most of her life on the run, but it’s impossible for an empath to avoid forming attachments. There’s no way she can abandon her friends, even if her loyalty means putting herself in danger. The solution? Hire protection in the form of a coldhearted killer.
By Asrai standards, Zedrik is defective. His people feel nothing, yet he’s always had the stirrings of emotion and enough curiosity to wonder what if. So far, he’s kept it under control. But when he’s suddenly faced with a determined, fiery empath who’s willing to sacrifice herself to protect her friends, he can’t say no.
With the Federation after them both, Alexis will have to trust someone to save her for a change. But is an “unfeeling” assassin the man to do it? If he turns his back on his feelings, he could finally secure a place among his people.
All it will cost is the empath he’s learning to love.