User blog comment:Miskos3/Fairy Tail Chapters 532 & 533, Review/@comment-7070784-20170422053208/@comment-2214433-20170422083047

Y'all need to finally realize that E.N.D. isn't a separate entity. E.N.D. is Zeref's perfect creation, his little brother revived. E.N.D. is Natsu. While Zeref did create Etherious with the intent to kill himself, he eventually used this method for his original purpose, to bring Natsu back. Once that happened, Zeref gave Natsu to Igneel in hopes that his "perfect creation" would become strong enough to kill him eventually.