User blog comment:FairyRaven/Fairy Tail Chapter 329: Seven Dragons, Review and Commentary/@comment-4643135-20130505013544/@comment-4643135-20130509042438

Yes I remember after Zirconis gave the first explanation for how he became a dragon, Arcadios and Yukino appeared and said that, with his research and the story they heard, "one can even speculate that Zeref made a dragon slayer into Acnologia." There a re just a few small nitpicks I have with his explanation. One, he says that it is speculation on his part. Two, the research he did might not any more decisive than the information they had on the Eclipse Door. I find Zirconis' explanation more reliable as he witnessed it himself. But that is not to say Zeref isn't what completed the transformation or that Arcadios is completely off in his claim. I just think Acnologia would have to have met Zeref halfway for the transformation to be as complete as it is. Halfway being already well developed the features of a dragon and Zeref just making the final adjustments.