Luke’s Crusade by Stephani Hecht

As an Assassin, Luke has learned to trust only a limited number of shifters – his fellow Assassin’s Loyalty members. When he makes a promise to one of his few friends’ new mate, Conner, to find the Mountain Lion that saved him, Luke had no idea that his world is about to change.
Calvin knew he couldn’t let the slavers capture his friend Conner – a rare Koala shifter – so he sacrificed himself so Conner could escape. After he killed his first master, he ends up on the auction block losing what little dignity he had left. He didn’t think things could get any worse until he’s purchased by an Assassin!

Both Luke and Calvin quickly find out that the other changed his world for the better – however there is a pesky problem of a bounty on Calvin’s head and why would Mitchell from the Coalition be visiting the mansion to speak only to Calvin?