The Prince of the Outsiders - Knights of Mellora, #2

Something wicked haunts Prince Forth's dreams: when he sleeps, he's a creature of decay and darkness whose appetite for death is matched only by its efficient lethality. Unwilling to tell his friends the full truth and barreling toward madness, he travels alone to the northern realm of Niranorn to prove to himself he's not a monster and to re-imprison the beast he's convinced has been unbound.

Queen Sorcha of Niranorn is new to her throne after her brother was brutally murdered by an ancient king twisted with dragon magic into a deathless killer. Her people expect her to unite the squabbling provinces of the realm and stop the savage attacks, but she's barely holding herself together. And finding a prince from a foreign land at the edge of her realm is a problem she doesn't need.

Despite her distrust of the outsider, Sorcha accepts Forth's help to find a way to stop the horrors in the woods, and soon a love both wild and comforting blooms between them. But as the evil that stalks the dark grows more powerful, Sorcha and Forth must work together to bring the realms of Niranorn together and stop the being from the iron casket before its bloodthirsty legions extinguish the living world.