Blood and Bone by Patricia Logan

Aristotle Brown is starting to like his new job with the U.S. Marshals Interspecies Response unit. If anyone would have told him vampires, shifters, werewolves, and space aliens existed a few months ago, he would have called them crazy. But meeting his new partner has proven to be the best part of the I.S.R. He’s settling into the new job and the new man nicely. When he moved out to Los Angeles from Lexington, Kentucky a few months ago, he thought he might try finding a guy, but he never expected to feel that way about his new partner.\
Eoghan Sapphire thinks Ari is beautiful and brilliant, and that’s probably a good thing since they spend a lot of time together. Very quickly, he realizes that the feelings he’s having for the man, aren’t purely professional. He wishes things would slow down but when work gets in the way, he realizes they can’t stop moving…not even for a minute. On the way to Northern California to help the local tribal police locate a fugitive shifter Eoghan once put behind bars, he and Ari drop in on a friend before coming face to face with a couple of unexpected predators. And if their life wasn’t crazy enough, a few insulted cephalopods give chase.
Better still, a case involving a vampire with a very unusual oral fixation, has both of them grateful for the blood-sucker’s restraint. Just when both men think things might settle down and there’ll be an end to the madness, they’re tasked to meet a couple of the scariest shifters they’ve ever heard of. And just to put a cherry on top of the assignment, it turns out these guys aren’t exactly the forgiving kind. As Eoghan and Ari enter a world neither could have prepared for, they come face to face with something thought to live only…in legend.