User blog comment:Stone Roger/Natsu and Zeref have somekind of relation?/@comment-4615055-20130508140823

My hypothesis is that Natsu and the other First Gen. Dragon Slayers (including Sting and Rogue) came from the era when the Dragon Civil War began and transported to the present time at some point.I came up with this guess because when you look back at the Fairy Festival arc when Freed put some runes in the entire city restricting 80+ years of age, Natsu and Gejeel both can't come out to the battlefield.