Van Helsing 2004 - What's does reside in Anna's "lusting heart"?

Anna ran through the woods, tears blinding her eyes. Her Brother Velkan was dead or worse. The hunt for the werewolves terrorizing the countryside had gone wrong. The trap had failed and the beast had broken free and attacked. Several of the hunting party had been killed, their rifles unable to do more than anger the beast, Velkan having lost his grip on the pistol loaded with silver bullets.