Tearfall

The Grays promised salvation. They brought Tearfall instead. A woman surviving on spite and pork jerky. An alien warrior honor-bound to atone for the mistakes of his people. A secret that will destroy the last of humanity. Captured and taken aboard the Grays' warship, Cat wants nothing to do with the alien warriors who destroyed her planet. But when she discovers that people are disappearing from the Safeties-and that humanity faces total extinction-she must help her enemy unravel the mystery.
As the truth emerges, Tavik faces an impossible choice: betray his kind and his creed, or defend the defiant human survivor who has upended his reality. And Cat, who has no desire to be a hero, must do the one thing the end of the world has taught her to avoid at all costs: trust someone with her life.