User blog comment:LastationLover5000/Speculation Time With Ahatake (Fairy Tail 297)/@comment-4728047-20120901014829

if specific individuals are granted the powers of the Dark Lord Zeref that may be the 'demon' part of this so-called 'gathering of dragons, demons and...' whatever that third thing was

and it also kinda goes back to whomever it was that had speculated that the reason for the 'Black (Element)' of God Slayers being somehow related to Zeref as well (during the loli fight)