Iron & Aqua (Blood, Bloom, & Water, Book Three) by Amy McNulty
A beguiling vampire. The besotted girl who agreed to be his champion. The ongoing battle to save not only the vampires, but also the world.
Ember Goodwin didn’t realize that falling in love would mean sometimes transforming into a vampire—or that she’d be able to shoot fire from her hand. Though she never wanted her step-sister to be her enemy, she can’t just stand aside and let the merfolk proceed with their wicked plans. After walking amongst the undead, she knows that vampires are the true heroes of the ancient conflict, and she’ll do what it takes to make sure they win—even if that means going against the sibling who got caught up on the wrong side of the war.
The third book in the Blood, Bloom, & Water series takes the war between fangs and fins to new heights as betrayals and secrets threaten to unravel even the best of intentions.