User blog comment:BlackWizardZeref/Fairy Tail: Chapter 436 Memoirs Review with a brief mentioning of Chapter 435 Victory Shout!/@comment-67.183.85.153-20150519044811

Based on your theory, which I like, it seems more likely to me that Igneel wasn't sent forward with Natsu: he stayed behind and was eventually half killed. Right when everything was about to go down, he sent his son forward