Killer (Sweetheart Alphas Book 1) by V.C. Lancaster

Wilson Carlyle is an omega in need of an alpha. Not just any alpha, but one with a special set of skills. Wil needs a killer.

A year ago, his parents were murdered by his cousin Dominic, who is in debt and in trouble. Expecting an inheritance that didn't come, Dominic is now after Wil and his company, and he will do anything to get them.

Protection from Dominic isn't enough for Wil, he wants revenge, which is why he needs an alpha mate to stage a legal murder in self-defence. To make absolutely sure, he spends a quarter of a million dollars on Jack, a feral alpha from an illegal alpha-fighting ring. With blood already on his hands, Wil is promised Jack is exactly what he needs. He doesn't care about the personal cost of mating an alpha like that as long as he gets what he wants: Dominic's head on a plate. After that, Jack is free to go with enough money to make all his dreams come true. That's the plan, anyway.

But what happens when Jack turns out to be a good guy, who loves his mother and wants to love his omega? When he's upset to discover their mating isn't what he thought it was? When he isn't happy being asked to kill one last time, and Wil realises he might have miscalculated?