User blog comment:FairyRaven/Fairy Tail Chapter 416: Tartarus Arc: Final Part, Review and Commentary/@comment-1776824-20150120211959

This is just an announcement for people that are: Igneel chose not to kill E.N.D. It says "could not" but it is in the context of he could not do it for some particular reason that was holding him back. Ergo he elected to lose and didn't finish him off for any particular reason. For those of you saying that Natsu and E.N.D. are some kind of fucked up twin... ...okay. >_> But for those of you that are curious and want some help trying to figure out the truth before we get any sort of development on this matter (idk, probably guess like a 12-18 months or so), use this to springboard.
 * 1) Forgetful
 * 2) Cannot read
 * 3) Too lazy to read the articles we have on the wiki
 * 4) Ignorant
 * 5) Anything else I did not mention (Oh come on, most of you fit into at least the forgetful category...)