User blog comment:FairyRaven/Fairy Tail Chapter 424: Avatar, Review and Commentary/@comment-24963954-20150316093101/@comment-9595671-20150316115704

I dunno, remember when Kaguya revealed who her brother was?

We might, Natsu does know who did it so I have a feeling that's why he knows they need to go there. Remember how Natsu was shocked when he heard it? After this chapter I think now I realize why he was.