Chained By the Cyborg by Alyse Anders

To keep her safe, he must bring her to the most dangerous place on the planet – prison.
As warden of The Prison, Zee ensures everything runs smoothly. But when he’s informed that he has a mate from halfway across the galaxy, his carefully controlled world gets turned upside down. To make matters worse, the man who betrayed him also has a mate who will stop at nothing to see him.
As a paramedic, Mags is used to jumping into danger to do what’s necessary to save others. When she realizes that Tara’s mate is a murderer, she makes it her mission to help keep her safe, while coming to terms with her intense relationship with Zee.
Now charged with keeping both women safe, Zee must fight against his blind lust for Mags to keep them safe in the most perilous place on Grus Prime.