User blog comment:Miskos3/Fairy Tail Episode 261: Tartaros arc: The Absolute Demon, Review/@comment-27247962-20151128091423/@comment-71.222.58.37-20151128182532

Well it has been stated by both Igneel and Zeref that Natsu will at some point have to fight END thus leading to the conclusion that END and Natsu mentally are two different people plus his Etherious form is currently unknown so theirs that as well.

For some reason when I picture END using curse fire powers I picture it as green flames, what do you think?