User blog comment:FairyRaven/Fairy Tail Chapter 365: Fairy in the Jail!, Review and Commentary/@comment-76.121.234.236-20131230020022/@comment-1359322-20131231102438

The third option makes me think, what if Natsu's new found intelligent is actually from Jackal. Maybe Jackal didn't actually died yet but infested himself into Natsu, he then manipulated Natsu into invading Tartaros HQ so that he can revive himself.