User blog comment:FairyRaven/Fairy Tail Chapter 301: The Dragon King, Review and Commentary/@comment-3970561-20120928192704/@comment-3970561-20120929190752

Probably Acnologia was Zeref's nakama! maybe he was helping him create a perfect world and he tried to transform him into a dragon in order to make him even stronger... but he obviously regreted it later!

I also thought they may be brothers but it's way too much! -.-'