Top 3 extreme personality changes!

[GodaimeRaikage]

Part 1 Itachi was portrayed as a murderous, cold guy. I'm not saying he was ,but he was portrayed that way and his personality changed because he stopped living a lie

Neji was introduced as a parallel to Sasuke. He was a resentful genius that believed in fate after he got tnj he became a badass shinobi that kept his cool no matter what (kinda like Kakashi). Once shippuden started he was forgotten, no longer strong, accepted his duty to protect Hinata and was no longer remotely relevant to the story

Just what I thought, you are using what was thought of a characters and not the characters actual personality.And Neji no matter how you try to word it, was always a side character. Neji once shippuden started was a jonin, was stronger than he was in part one, and still had the same demeanor as he always did.Now you might be disappointed in his development, i am also, but the fact remain his personality was the same.Also, Neji was never relevant to the story other then being a stepping stone for Naruto to advance his dogma, I.E. Neji in part one was only a plot device.Once Neji serve his purpose in part one there was no longer any need for him until he was killed off, again serving as a plot device for Naruto to spread his dogma.You believe that Neji was introduced as a parallel to Sasuke, but this is false. Neji was consider a genius even greater than Sasuke, but Neji unlike Sasuke isn't a main protagonist.Your post is focusing on Neji personality when you actually are hinting at Kishi lack of character development of Neji.