User blog comment:IamJakuhoRaikoben/Chapter 366: 1000 Souls, Review./@comment-24066070-20140113023343/@comment-7418318-20140114084432

The problem with Natsu, as I see it, isn't that he has no character development, but that whenever it happens, it doesn't seem to stick.

Either his development is happening and then immediately forgotten and never has any consequence for the story (like his admitting how strong F-Rogue is) or used once or twice and then forgotten (like the "lesson in fear" he got from Gildarts, that played a role against Zancrow and Hades, but never after).