After the ravaging, the vampire populace restructured itself into a new society. However, vampire hunters did much the same thing. What were once widely disparate groups (The religious Society of Leopold, the secular Twilight Agency, the occult Arcanum, etc) have consolidated into one monolithic group, The Agency.
Overall, The Agency appears to act like any other hunting group, only moreso. They have greater resources, more members and, most devestatingly, more knowledge. They also have the backing (to a limited degree) of the government, but appear to be an entirely private enterprise.
The Agency should be avoided at all costs, if they catch wind of you they will not stop until you are extinguished. It is best if they are simply ignored.