Ink Sworn by Alessa Thorn

Valentine has always had perfect control over his darkness— except when it comes to the one deceptively sweet female whose hidden claws match his own.

Scarred by dark magic and deadly visions, Valentine has spent years binding his dragon deep inside—until the disappearance of Yelena and Avallach forces him to unleash the beast.
Born wild and abandoned to die, Yelena has learned to hide her true nature behind sweet smiles and pale silks. But when ancient enemies threaten the fragile peace between worlds, Yelena must choose between her safety, or the dangerous sorcerer whose darkness makes her dragon purr.
As ancient enemies close in and trust shatters, Valentine and Yelena must harness their volatile magic while healing the wounds that shaped them into monsters. Because some bonds are forged in blood and fire, and true love means accepting the beast within.