She trembled lightly and when he bit her, she came, hard, clenching his member as she did.  She arched her back and writhed beneath him.  She felt him feeding from her potent blood.  It wasn't the taking blood from her that would make her his, it would be the giving her his blood.  If he drained her, he'd make her like him...of course, was that his goal? Or did he wish to keep her human.