User blog comment:FairyRaven/Fairy Tail Chapter 416: Tartarus Arc: Final Part, Review and Commentary/@comment-24367018-20150119232736/@comment-25324252-20150119235952

We have known for a long time that Natsu and END have a connection and now we know END is Etherious Natsu Dragneel, it only makes sense that END and Natsu are the same being. The book likely seals away Natsu's true power and personality. He is probably a special case. I don't buy into an evil twin theory