Saving the Omega by Tamsin Baker

In a world where only paranormals survived…
A cruel virus wiped out all humans. Now there’s a war between the supernatural factions…

Life is bleak for Angus. As a wolf shifter, living under vampire rule is intolerable. He hates the rules. He hates their power. He hates not having control over the lives of his pack.
He keeps himself under tight control…until he cracks. A young wolf is being beaten by his mate. Unforgivable. Angus reacts and everything changes. Saving Clayton may just turn the tide for everyone, including the true Alpha in Angus.
This new world for Clayton is hell, and living with an abusive mate makes everything worse. But when Angus saves him from that torture, for once in his life there is an inkling of hope

With jealous pack mates and vindictive rival gangs on their doorstep, danger is around every corner. Can Clayton pull on his Omega strength for his Alpha, and will Angus accept the love only his true Omega can bring.