User blog comment:Miskos3/Fairy Tail 526: My Name Is..., Review/@comment-24053170-20170313203914

Ok, so August is Zeref and Mavis's actual child. I get that. But it still doesn't explain the massive plot hole from many chapters back about Larcade-

"Only his mother can defeat him." -August

From the way he said that, I don't believe he was referring to himself at the time.

So unless Mashima decided to retcon the entire story after that chapter, then it seems like August honestly believed Larcade was Zeref's son.

This chapter seriously messes up the overall continuity of the series and leaves countless unresolved plot holes....