His huge debt.

He was confused...

"You must catch him, you must kill him!" 

The boy kept on running, he persisted and did not allow himself to be killed by his pursuers just as they did to the other of his kind. He looked at the rabbit in his hands, the pure white bunny had been reduced to a lifeless rag. The boy threw it aside and wiped his blood-stained lips. He ran his tongue over his fangs and looked back. He could hear voices and was sure that they would catch up with him soon. With the little blood he had taken from the rabbit, it seems that he would only be able to run for less than an hour before they caught up with him and kill him.