User blog comment:FairyRaven/Fairy Tail Chapter 435 & 436: The Cry of Victory & Memoirs, Review and Commentary/@comment-24277053-20150518124050/@comment-115.241.39.191-20150518153204

Because Natsu was restored that it took long time.I mean Zeref' s purpose was only to bring him back and also to die by his hands.I doubt if it is a demon.