Dawn of the Cyborg by Marie Dry
On a future earth, Aurora has been desperately searching for her long-lost sister, when she is sacrificed to Balthazar, leader of the fearsome Cyborgs who invaded earth. Now she is stuck on an alien spaceship with a crazy Cyborg who thinks she can give him a soul and who has a weird fixation with the way she moves. Aurora is desperate to return to earth to search for her sister while the president of United Earth insists that only she can save Earth from enslavement by the cyborgs. After spending time with the cyborgs, Aurora realizes that the machine she thought would be easy to betray, the machine she has to betray, if she ever wants to rescue her sister from enslavement, has turned into a man she could come to love.