That would be an entertaining method of keeping score - although that would probably also be futile if they got so caught up with the sound of the other crying out that score didn't become important anymore. In any case if it had been something they were doing, Natsu would already have had the advantage from the soft moans he'd gotten out of her already.

And.. oh; feeling his tongue against her lips trying to gain entrance, she obliged him eagerly parting her lips with her tongue moving to meet his, the hand in his hair giving a slight tug reflexively.