In the Fighting Festival Arc, Natsu and Gajeel couldn't go through the barrier made by Freed's Runes,
In Tartaros, the reason was revealed as the Dragons that were inside their bodies, although that wasn't conclusive enough, and in this chapter as an added bonus, we realized that Wendy (the conversation between Igneel and Grandeenay after the Fighting Festival Arc comes to mind), Sting and Rogue are all from the past as well,
In Tartaros, Igneel specifically told Natsu not to destroy the Book of E.N.D....and in this chapter any damage to the book directly correlates to Natsu...
At the beginning of Oracion Seis, Natsu knew Wendy from somewhere when he first met her, and it's confirmed this chapter they were together 400 years ago....HOLY ****ING ****!!!
I call this foreshadowing at its finest
Seriously this makes so much sense and why the dragon slayers are terrible at modern transportation. It is way out of their time or understanding!!!
This chapter is ****ing amazing!! Mashima is the KING!
Don't forget when we found out that Lucy's mom disappeared the same day the dragons "disappeared". Now we know why.