User blog comment:IamJakuhoRaikoben/Chapter 503: The Last Sight Seen, Review./@comment-5303512-20160926122525/@comment-5303512-20160927202119

Nastu/END is not all gone for your information, he is still able to contemplate language and knowledge of his "former" allies. The demons are under the programming of "killing Zeref" too but you don't see them being all beastly, while most of them are under the impression of "return to Zeref" as far as I am concerne, they are the same purpose. With Natsu's case as END, it seems a little more is going on first glance.