Anita's arms start to shake from the effort of holding him back, and Damian's teeth continue to press closer to her throat. She screams for help, and suddenly sees Gregory above her, pulling on Damian's arms. It's enough to slow, but not stop, the descent.

If Damian were just a rouge vampire, Anita could probably have killed him, even unarmed as she was. Damian not being a master vampire, it was possible that the metaphysical boosts she's built up would have been strong enough to tear his throat out with her bare hands. Simply stopping him, though, was a much harder proposition.