We Were Meant to Burn by Nicolette Elzie

A mercenary with secrets. An assassin raised to be a weapon. A love that was never meant to survive.

Nix Zaldanna was never meant to fall in love. As the infamous Nightshade of Rojas, she was trained to kill, to obey, to serve. But when she is captured and left to rot in the dungeons of the enemy king, she waits for the Empress to come for her.
Except the rescue never comes.
Instead, she’s freed by Malakai—a fae warrior whose loyalty is as questionable as his past. He claims he needs her, that she’s part of something bigger than the war she was raised to fight. But Nix doesn’t trust mercenaries. And she especially doesn’t trust a man who makes her question everything she’s ever known.
But the more she fights him, the more she fights herself. Because the war isn’t as simple as she once believed. And neither is Malakai.

Betrayed by the empire that made her, bound to a man she doesn’t trust, Nix must decide whether to burn for the future she was promised—or forge a new one in the ashes of the lies she’s been told.