Zone Cyborgs Series by Jessica Marting

One stupid decision leaves Cressida stranded on Haven, an uninhabited planet on the edge of nowhere. But it isn’t totally empty. And Lukas, the cyborg living there in secret, is fascinated with her and has no intention of letting her leave.

Petty sabotage knocks Matthias’s freighter off-course to an uncharted moon, but before he can right his ship, a distress call lures him to its hidden compound and the beautiful woman trapped there. Confined to a luxurious prison for years, enhanced until she’s a machine in a human body, Serena is desperate to escape, even if doing so could mean her death. But if she’s going to die anyway, she may as well really live while she still has the chance.

To get her life back together, Valenna Merchant has to leave Echo-7. When the chance to escape to a remote military base on Omega-Three-Omega via a housekeeping job emerges, she takes it. But nothing on the base is as it seems, including the cyborg, Anders, kept in a giant water tank for research purposes. And when Valenna uncovers the real reason behind her job offer at the base, she realizes she has to escape or die trying. And she’s taking Anders with her.