User blog comment:IamJakuhoRaikoben/Chapter 515: I Am You... You Are Me, Review./@comment-5708675-20161221121613/@comment-7418318-20161221122128

"He could turn a human into a dragon but not back"

What do you mean? Sure Archadios said that he suspected that Zeref was the one who turned Acnologia into a Dragon, but that theory has been thorouly disproofen by Igneel's words already and now we even got to see it (more or less) first hand with Irene in this flashback.