Court of Secrets and Flames by Nina Frost

She’s a pawn in a deadly game. A game for which she doesn’t know the rules.

One moment, Lark Axton is just a trainee at Flighthaven—a noble daughter of Aclaris training to fight the winged enemies from Tirene—who’s embroiled in a forbidden love affair with her gorgeous trainer, Sterling.
The next, she’s reeling from the worst kind of betrayals. Now, she doesn’t know who she is. Or who to trust.
Because Sterling isn’t a flight trainer. He isn’t even Sterling. He’s Prince Knox of Tirene. And he’s kidnapped Lark on the orders of his older brother, King Jasper, who claims Lark is Tirenese and seems determined to court her.
Held hostage in the Royal Palace, Lark soon realizes she may be the subject of a prophesy written before her first breath. One that could cost her life. Her heart torn by betrayal and her mind consumed by more questions than answers, Lark is soon ensnared in a dangerous game.
But perhaps the greatest danger of all is Sterling. One look from him can ignite a blaze hotter than the fire magic she’s suppressed her entire life. Caught up in a realm of intrigue where there’s a fine line between love and hate, Lark must choose between the world of her past and the one that holds her future…a future threatened by a sinister, slumbering evil that’s awakening to consume them all.