User blog comment:Sargenttacos115/Natsu and Gajeel age Theory/@comment-71.241.245.36-20141101223449

Now it is quite obvious from the recent chapters. WARNING SPOILERS IF YOU HAVE NOT READ RECENT CHAPTERS!! YOU HAVE NOW BEEN WARNED! Basically Igneel was inside of Natsu somehow (and probably the other dragons are inside their dragon slayers). Igneel came out to fight Acnologia when the guild was fighting the dark guild Tartoros made up of demons from the book of Zeref. So Igneel is probably at least a few hundred years old. So since he was inside of Natsu that means that Natsu couldn't pass the barrier since Igneel was inside of him.