User blog comment:Derax-Pagani/Chapter 507: Voice/@comment-4449950-20161028023156/@comment-7418318-20161028143111

Irene didn't seem particularly hostile to me.

Sure she sent Neinhart to kill Erza, but that looked more like she herself couldn't be bothered to do it herself, so she sent a flunky to do the annoying task.

"And the fact that the portal between Earthland and Edolas is closed. And plus the last bit of text that this was the last time they saw each other."

If it's possible to open an anima from Edolas to Earthland, I don't see why the reverse shouldn't be possible too. Why anyone would want to we can only guess at.

It's also possible that magic never was truly finite in Edolas, but that it's recovery rate is just very, veeeeeeeeery slow. So slow that they constantly used up more than was recovering naturally which led them to the wrong believe that it was not recovering at all.

For all we know in those 8 years since the Edolas arc, magic might have recovered sufficiently for them to once again open Anmia if they wanted to. If so, there might even have been a civil war between hardliners who tried to aquire magic at any cost like Faust did back in the day and those who thought like King Jellal that morals come before convenience.

If she broke with the king and was soundly defeated by "her world" it might explain why she abondoned Edolas and chose to join Zeref instead. Or maybe she rejected Erza's words about life being more important than magic after thinking it through and now she holds Earthland responsible for ruining Edolas and thus wholeheartedly supports his plan to wipe out all Earthland Humans.

The varient that Misk speculated on I think is rather unlikely. Not with both that mechanical Dragon and the Reverse Anima sucking the entire planet dry.