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 werewolf terrorizing the countryside had gone wrong. The cage had failed and the beast had broken free and attacked. Things had started going wrong at the beginning for the hunting party. First, the hoist had failed to get Velkan fully any from the beast, Anna managing to distract it long enough that the cage could deploy and capture the beast. But then the beast thrashing about caused Velkan to lose his grip on the pistol loaded with silver bullets. The hunting party had tried to help, but their rifles only angered the beast, while managed to get her hands on the revolver. But the werewolf burst free of the cage and chased her to the edge of a cliff. She'd turned to face it, but Velkan had arrived, pushed her clear while taking the gun but had been knocked off the cliff after shooting the lycanthrope.

"That cliff was too long of a drop for him to survive, so my brother is dead. The only way he could have survived is if the wolf infected him and now, he'd be doomed to become its replacement!", she lamented. Her family had been fighting monsters for generations, but now it seemed hopeless. Mother and Father were gone, Velkan was dead or lost to lycanthropy and she had to face the threats of Transylvania alone. Especially the one monster her family had sworn to kill, but had never managed to cause more than passing harm, Count Dracula.