User blog comment:Miskos3/Fairy Tail Chapter 486: The Fourth Guest, Review/@comment-6401212-20160524052444/@comment-7418318-20160524101418

We know for a fact that Zeref both modified Humans (or at least one) to become Demons and created some Demons out of nothing through Living Magic.

Bradman could be anything. Maybe a different version of Demon, an improvment on Keith or maybe a new experiment that he made only recently (as within the last 100 years ^^ - recent only compared to the Tartaros Demons :P ).