Cassandra had been hunting for vampire her whole life, her father was a vampire hunter and his father was one too, so it pretty much ran in her family. Unlike all the other vampire Hunter's, she was special.

Cassandra could hear a lot better, she could smell things a lot better, and she could also run a lot faster. As soon as Cassandra laid her eyes on you, she made sure to hide herself in the Shadow's so that it was harder to spot her. You've become her prey.