Dance of Thieves by Mary E. Pearson — book slip

In the world of the Ballenger empire, power is everything. When the patriarch dies, Jase Ballenger steps up as the new leader of this outlaw dynasty, a family that rules by its own laws. But the arrival of Kazi, a former street thief turned soldier for the new queen, threatens to upend the balance. Tasked with a mission that could alter the fate of kingdoms, Kazi finds herself entangled with Jase in a web of secrets and political intrigue. As enemies become reluctant allies, their growing attraction is as dangerous as the secrets they keep.

First in the Dance of Thieves duology, set in the world of the Remnant Chronicles.