Kiss of Crimson by Lara Adrian

After a brutal attack that leaves him close to death, Dante, a Breed warrior, must bite Tess, a vetrinarian, in order to stay alive. Only afterwards, does he realize that she is a Breedmate and he has performed half of a bonding ritual that will tie them together for eternity. As Dante and Tess struggle to come to terms with the electric connection that pulls and ties them together, the Breed Warriors must battle a new threat - a drug, called Crimson, that turns vampires rouge.