Fire with Fire by Destiny Soria

Dani and Eden Rivera were both born to kill dragons, but the sisters couldn’t be more different. For Dani, dragon slaying takes a back seat to normal high school life, while Eden prioritizes training above everything else. Yet they both agree on one thing: it’s kill or be killed where dragons are concerned.

Until Dani comes face-to-face with one and forges a rare and magical bond with him. As she gets to know Nox, she realizes that everything she thought she knew about dragons is wrong. With Dani lost to the dragons, Eden turns to the mysterious and alluring sorcerers to help save her sister. Now on opposite sides of the conflict, the sisters will do whatever it takes to save the other. But the two are playing with magic that is more dangerous than they know, and there is another, more powerful enemy waiting for them both in the shadows.