Defender of Shadows by Anna Volk (Living in Shadows Book 3)
Blurb: Marcus has spent years walking in shadows and then hiding in shadows. It almost destroyed him and sent him into exile. Now, in the final book of the Shadow Series, he must step up and defend those shadows. He must learn to trust and accept help in order to receive redemption. He also must protect the woman he loves who, seemingly against all odds, loves him despite the shadows that lurk within him.