The latest Chapter 465: 400 Years has been released and it had the big revelations that Zeref is Natsu's brother and that Natsu is the END (Etherious Natsu Dragneel).
Natsu fails to defeat Zeref and Happy stops him from his last chance to strike with Igneel's power. He loses his one last shot to kill Zeref-which would also result in his own death.
Zeref reveals that he wanted Natsu to be the one who would end his life, which is why he sent him to Eclipse. However, after 400 years, Zeref no longer wanted that. With Natsu out of the way, what does Zeref have in mind?
"You can't stop me anymore. Goodbye Natsu" - Manga Panda Fairy Tail. Ch.465.
The next chapter is entitled "Assassin" and with the big reveal done, the big questions remain.
Will Natsu tell Fairy Tail about what he learned-that he is one of the most evil creatures, the vilest demon created by Zeref? How would Gray react?
Manga Helpers users believe that Natsu will tell the truth (perhaps about the dragon slayers) but will leave out the part that he is END. It's also likely that Happy won't either, knowing that such a revelation will cause chaos in the Guild.
Who is the "assassin" in question. User 'sarahmavis' suggests: "when I think of "assasin" I think more about Brandish still beeing captured in the FT guild and her underling jumping around freely."
The connection between Brandish and Layla is another big mystery that has yet to be revealed. Layla played a key part in transporting the dragon slayers through time. Does Brandish know that-is she against it and if so-why? Or could there be an entirely unrelated reason?
But there's another interesting angle, presented by Reddit user Vborz 253:
"Regarding Lucy... Next chapter's title is Assassin. Layla died in the same day she opened Eclipse. We have 5 possible murderers (who met her after going through the gate): 4 humans and a demon... What if Natsu killed Lucy's Mother and doesn't remember it? Would be quite interesting if that hapenned plus Brandish knew that somehow and decided to start a shit storm in Fairy Tail when Natsu arrived."
That would explain why Brandish was captured too easily. She wanted to be inside the guild when she makes the big reveal-in front of Lucy and Natsu.