User blog comment:FairyRaven/Fairy Tail Chapter 435 & 436: The Cry of Victory & Memoirs, Review and Commentary/@comment-26389992-20150518133328/@comment-1359322-20150518154348

Considering how no one in Tartarus realized Natsu is E.N.D. i'd say how things develop from everything we learnt in this chapter is still a mystery.