User blog comment:IamJakuhoRaikoben/Chapter 234: The Boy Who Stares At The Sea, Review./@comment-3174518-20110518233146/@comment-1839664-20110519003343

I don't think it's Mavis at all. Being the one that created the Fairy Tail guild, that means that he must also have created the mark of Fairy Tail. Since this character already has a mark on his shoulder at a young age, it's highly unlikely that its Mavis. Zeref, however, may be possible. It may also explain why Natsu couldn't get out of the barrier during the fighting festival arc.