Beast of Burden by Ariel Millar

Orion:
When the Alpha Zane Bereket goes missing, it’s up to me to find him. As a Beta Wolf and Kor’s second-in-command, leaving the compound is dangerous, but Zane is the one Alpha who has always been under my skin. And in spite of knowing we can never bond, I couldn’t live with myself if I couldn’t bring him home alive.
Luckily, Zane’s brother has a plan. He’s concocted a formula which will allow me to pass as an Omega and steal the information from the city on who has been taking our Wolves and where. What neither of us knows is whether or not I’ll be strong enough to rescue him as an Omega, and whether or not I’ll make it back before Zane’s lost to me for good.

Zane:
For months, my world has been nothing but blood and violence. I have long-since lost track of anything except the beast inside me, and obeying the commands of my human Masters. But when a new Wolf turns up and takes me from that place, I realize there’s more to who I am than just a monster. His scent is familiar—and yet entirely new. This Omega is different, and he just might be the only thing that can bring back the Wolf I once was.