It was only by being a Marine and an agent of SHIELD that he had that level of self control. He watched as Rebekah let the girl go after compelling her. He rose to his feet as the older vampire turned to him and he stared at her. From what he had learned since arriving in Everett his life was essentially tied to Rebekah's now. If she was killed he would die.
At her question of still being hungry, he swallowed. "I am..." he confessed, glancing down in slight embarrassment before looking up at her. "Is that normal?" Whether he liked it or not, he needed to learn all he could from Rebekah about being what he was now. The better prepared he was and all.