User blog comment:FairyRaven/Fairy Tail Chapter 435 & 436: The Cry of Victory & Memoirs, Review and Commentary/@comment-6904925-20150518110318/@comment-5268982-20150518205829

For me Natsu and Zeref =/= brothers. I mean, Zeref certainly believes Natsu is one, but his brother's body was just a vessel for a completely different entity.