User blog comment:FairyRaven/Fairy Tail Chapter 372: Breach, Review and Commentary/@comment-7418318-20140221095739/@comment-5268982-20140221101125

I am almost certain that this is indeed Zeref. I agree that there are still many loose ends, but that shouldn't stop Zeref from appearing, delivering a message and going away again. On the contrary, it may be unexpected twists to this arc that last chapter began going downhill, and it may also help develop Natsu's character. That's why I hope and am ready to buy that this guy is in fact Zeref.