Following the events in the previous chapter, chapter 503 of "Fairy Tail" is expected to see Natsu's E.N.D.
In the book of Zeref, E.N.D. is a legend that fans have never been witnessed yet in the series. There are speculations that in the upcoming chapter, Natsu will finally tap into his inner E.N.D.
The previous chapter revealed that Natsu's shrunken tumor was neither a tumor nor an anti-Ethernano. The events in the chapter revealed that it was something far worse than either of the two.
Fans speculate that in chapter 503, Natsu's supposed tumor will trigger something in him that will compel him to tap into his hidden strength, which is the legendary E.N.D. It is possible that Dimaria will be the first one to experience this unparalleled power of Natsu, since he was the one that Natsu was last seen with in the previous chapter.
Titled "Last Sight I Beheld," the upcoming chapter is also expected to feature Brandish as he attempts to end Dimaria's plans. The chapter may also reveal the real relationship between Eileen and Ezra. In chapter 502, Eileen tried to get the Fairy Heart from Mavis. However, Mavis tricked Eileen and used her illusion powers to escape her clutches. As Eileen stumbled upon the real Zeref, the latter pointed out to her that she had been fooled by Mavis. This caused Eileen to come after Mavis. Fans speculate that as she chases her in chapter 503, Eileen will come face to face with Ezra.
"Fairy Tail" chapter 503 is expected for release on Sept. 28 on the "Weekly Shounen Jump."