A Hex for Hunger: A Romantasy (The Rune Tithe, 2) by Alistair Reeves

After five centuries, a loyal guard returns from the dead without the king he once served―and loved―to find the world and his place within it much changed. Ambrose aka the Grim Wolf of Belgrave spent his life striving to be a hero―until he died a villain in the name of the medieval witch king he was passionately devoted to. Now, after hundreds of years, he’s back from the dead without his beloved king. And the vow he once swore has him obligated to Emery Vale, a necromancer-in-training, who’s tasked him with murdering his rival and nemesis. But Ambrose has other plans. He hopes to bring the ruler of his kingdom―and his heart―back from the grave so they can finally enjoy the love they’d once yearned for. All he has to do first is kill one other person: Emery . . . The more time Ambrose spends with his new master though, the more his hunger for Emery’s blood is turning into a hunger for Emery. And as he continues to search for a way to resurrect the witch king, he might just discover their connection wasn’t all that it seemed.