User blog comment:FairyRaven/Fairy Tail Chapter 363: The Stories That Demons Read, Review and Commentary/@comment-112.133.212.13-20131206131123/@comment-1359322-20131206144819

And the next thing E.N.D. turns out to be a female and is Natsu's mother. And the reason why Igneel failed to kill E.N.D. is because he fell in love with her.

Well that probably won't happen though.