User blog comment:B214/Chapter 503: The Last Sight Seen/@comment-5303512-20160926122648/@comment-1359322-20160928084439

It's the same thing. Etherious are Etherious it matters not how they are make. Fact is all Etherious are made to kill Zeref yet they showed that they can still deviate from that goal. For one Deliora never seem like he was aiming for Zeref instead he was just rampaging around too. So having no reason to kill anyone besides Zeref, is not a good answer.

For starters, your contradiction is quite obvious, "it could be that they are so beneath him that they are just a waste of time for him." Then why didn't Natsu ignore Gray? Before that, this here either "she stood in his way or Natsu had some sort of sanity left to protect Lucy before letting the demon take hold." Natsu can still tell who Gray is, if he's truly taken over by the "demon" as you said, why the hell did he even bothered to even focus on Gray at all. If END is truly only focusing on Zeref like you said, he could've just move on ahead without shifting his attention to Gray at all.

Besides, Natsu is determined to kill Zeref even before this. There's nothing to prove your so called Natsu becoming "wrathful, hateful and violent out of no where". He didn't kill Dimaria, he rescued Lucy and he didn't even attack Gray at first sight. If Natsu truly became so "wrathful, hateful and violent out of no where" like you said, the fact that Dimaria is still alive is already bullshit. Dimaria was about to hurt Lucy, you think Natsu who is easily angered whenever his friends get hurt would let her live at all if he has indeed become in your own words "wrathful, hateful and violent out of no where".