The Diviner by Brynne Weaver

Quinn has a rare and powerful gift, one that manifested from the rage and trauma of her harrowing childhood. Years later, the anger she can't let go of makes her an unpredictable and dangerous weapon of last resort for a kingdom on the brink of war. Diviners like Quinn are venerated yet feared, protected yet exploited. Bonded to the Queen, they are forced to endure hardship and sacrifice to protect her empire. After a near loss in a key battle and the death of the Diviner of Fire, the Queen calls for aid from the elite soldiers of the allied territories to the East. A striking warrior named Kiran is assigned to protect and train Quinn, and as the pair become close despite the rules that bind them, they discover that the enemies within are just as dangerous as the ones at the gates.

Time is running out for Quinn to harness her power. The enemy is closing in around them. Impossible sacrifices haunt every decision Quinn makes. As she fights to keep what little she's claimed as hers, Quinn learns that her destiny might not lie in the hands of fates or kingdoms, but in her own.