Night-blooming Hearts by Megan Derr

Phoenix sacrificed everything to become one of the greatest necromancers in nightwalker history—including his beauty, though that was by accident rather than design. As beauty is everything to vampires, he has been a pariah ever since, disowned, discarded, and largely forgotten by everyone he once called family and friend.
Nowadays, he lends his skills to sorcerer Jackie Black and the notorious Clan Mordred. If he still feels lonely and isolated, and rejected by the man he’d been stupid enough to think returned his interest, that’s his own problem, no one else’s. He’s used to rejection anyway.
Then his brother shows up on his doorstep begging for help with a blackmail problem—and offering the one thing Phoenix cannot refuse as payment. But if there’s one thing he’s learned about nightwalkers, it’s that nothing is ever as it seems, and problems always get worse before they get better…