Backslide

Eighteen-year-old Emma Harper has a prisoner. The worst lesson ever taught her the hard way to shoot first, and she'll never forget it. Now she gets to try to make him a friend. To use him.
At least she has a ton of practice. Her so-called friends used her for years.
When she and her Marines discover half of what they've learned about their sector of space is a lie, they'll all have to decide what really matters. Do they want to risk everything for another shot at going home? Or will the truth make them stay and give up the chance to ever return to Earth?