Flame and Sparrow by S.M. Gaither

On the eve of her twentieth birthday, Karys woke to the sight of a divine creature dying outside her home.

Two weeks later, her sister disappeared, leaving nothing but a trail of blood in her wake.

Convinced the gods were responsible for the disappearance, Karys has spent the past five years plotting her revenge with the help of a cutthroat band of likeminded elven rebels. So when Dravyn—one of her world’s most powerful deities—descends upon her kingdom in search of humans worthy of serving him, Karys knows what she must do. Earning a place at the god’s side will allow her to find out what truly happened to her sister…and then destroy the gods from the inside out for what they did.
Thrown into the dazzling but deadly world of the divine courts, she must navigate complicated politics, strange magic, and dangerous trials to prove herself worthy of standing among the gods.

Among the most dangerous of these trials is Dravyn himself.
Karys knows better than to trust the enigmatic God of Fire. The flames of passion that stir between them are only divine trickery. And yet, the more she learns about him, the hotter the forbidden sparks burn. The more she begins to question all she thought she knew about the world of gods and mortals and everything in-between.

And the more she risks betraying her own secrets, which may be the most dangerous thing of all.