The Mercy of Dawn by Ashley Bresee

“Can a daughter born under the sun of day find her heart a home bathed in moonlight?”

Cyril Rhodea has always feared the Kingdom of Reykr.
Generations of dark fables shroud the isolated moon-fae realm, its reclusive people steeped in rumors of ritual sacrifice and sanguine arts—a stark contrast to the orderly, conservative sun-fae states of Southern Carinae.
Yet when a contract to investigate murders plaguing the notorious kingdom is awarded to her uncle’s esteemed guild of rogues, Cyril is forced to confront those long-standing fears.
Reykr’s prince commander is a man she should despise, and not just because he’s determined to get under her skin. Mikael exudes abrasive arrogance, just like the foolhardy recruits who never last long at the guild.
But when tragic flaws surface in Cyril’s once-infallible family of rogues and she faces the reality of a life once loved being laid to waste, Mikael is the one standing by her side in the wreckage.
Torn between the conflicting pulls of duty and desire in a world determined to break her, Cyril knows only one thing for certain: No one will leave Reykr unscathed.