From Inside the Grey House:
Natalia caught the handkerchief, bringing it quickly to her now torn left breast. Vincent had bitten her on the side of her breast, leaving an ugly gash. She ripped her button-down shirt open, pressed the handkerchief to her wound, and let her bra hold the fabric in place. She tied the shirt in such a way as to stop her blood from flowing too much. She guessed correctly that Vincent knew exactly were to bite her in order to avoid major blood vessels. The handkerchief was stopping the blood quite well. Bastard.