Perhaps she uses her emotional abilities. Darker emotions such as anger and fear are hard to push onto a person for her, but not impossible. What if, before he could even do anything with his ability, she pushes that fear onto him without him realizing? Like, he has no idea why he's afraid of her, but he is. Where as, before she can kill him, he uses his powers on her as well. Kind of putting them in a loop. He can't kill her because he fears her for some reason and him putting her into those visions if she tries to lift her gun on him (him likely disarming her after the first try).

I'm wondering that too XD For her, I can see her using him to learn more about the Lunairans and use him as leverage to figure out how to survive. A 'I hate you but need you' sort of thing. Not sure if there would be anything about her to draw him to work with her.