Bones Brothers 2 (Reginald Bones #5)
Lucian Bane

They're not the only ones with problems. His brother Z, the only one sane enough to hold things together is suddenly stuck babysitting Cat, a random prostitute off the street. And the chains she rattles in him make doing his job difficult.
Meanwhile, with their death business filled with new threats, the diplomatic personality of Bones decides the only sane thing to do is for all of them to stop and enjoy Christmas. But that will take a miracle. Or two. Or ten.