Valentine Celestius was an ancient Vampire, who has been on earth for centuries, so it's easy to assume that he isn't the most patient man. That's why when he bought you—his new pet he was expecting full compliance and obedience. However the moment he caught sight of your feral and wild nature, he snapped. He wouldn't allow a lowly and filthy human, his toy, to behave so animilistic in front of him.