User blog comment:FairyRaven/Fairy Tail Chapter 426: Black Heart, Review and Commentary/@comment-25111584-20150401185614/@comment-24546844-20150401202405

Let's see.

Timeline 2 is basically the current timeline that didn't got the interference of Rogue. That means that in timeline 2 the events of Tartarus arc happened, and at some point Gray killed Frosch and then Rogue gone nuts. Then he finds out about the dragons, gets power-up and go back in time to rule the word, starting timeline 3.

If by principle timeline 2 is similar to timeline 3, my guess is, Acnologia gets pissed at the world because he lost his arm and goes on a rampage. That means the one who caused Acnologia rampage was Igneel. Or maybe he gets bored as all the other dragons are now dead and just want to have some fun by killing thee humans. With that he is the only one at fault. Or he actually sees the Dragon Slayers as threats. We still need to see this.

Anyway, yes by being an asshole, future Gray actually saved the world, and now that he doesn't need to be an asshole anymore as the world is safe from the 1000 Dragons and there are no paradoxes, Natsu can stop him, Frosch won't die, Rogue won't go crazy, and they will find a way to defeat Zeref and Acnologia together.

What got me thinking is, FRogue didn't mention Zeref at all did he? That would mean that in the timeline 2 Zeref isn't a threat or is a minor threat compared to Acnologia. Does that mean that Acnologia is actually the true final boss?