The Mercy of Gods by James S.A. Corey (SciFi)

How humanity came to the planet called Anjiin is lost in the fog of history, but that history is about to end.

The Carryx—part empire, part hive—have waged wars of conquest for centuries, destroying or enslaving species across the galaxy. Now, they are facing a great and deathless enemy. The key to their survival may rest with the humans of Anjiin.

Caught up in academic intrigue and affairs of the heart, Dafyd Alkhor is pleased just to be an assistant to a brilliant scientist and his celebrated research team. Then the Carryx ships descend, decimating the human population and taking the best and brightest of Anjiin society away to serve on the Carryx homeworld, and Dafyd is swept along with them.

They are dropped in the middle of a struggle they barely understand, set in a competition against the other captive species with extinction as the price of failure. Only Dafyd and a handful of his companions see past the Darwinian contest to the deeper game that they must play to survive: learning to understand—and manipulate—the Carryx themselves.