He really was liking this girl more and more. "I would never act like a monster," though he then thought for a second, "Well unless someone's being mean to someone else I guess." He never liked bullies or people like that, so he probably would indeed act like a monster against people such as that.
He contemplated for a moment, and came to the simple conclusion that she must have meant that to be a, I've seen monsters and you aren't one, type of comment, "You don't need to say sorry," he did his best to smile before continuing, "I'll take it as a compliment."
Though she seemed a bit strange, he was truly admiring this girl. She was very kind to him, and he liked her way of thinking, even if it was a bit odd.