User blog comment:IamJakuhoRaikoben/Chapter 451: Fairy Heart, Review./@comment-24438112-20150907085455

I think that Natsu slowly becomes a dragon and under his bandages he has scales or something as powerfull as a dragon to use it against Zeref. I also have a theory that E.N.D. is actually a Natsu that can turn into a dragon at will like Acnologia.