Well, it could be due to a plot twist in the fanfiction. The author might want to show Naruto's growth in a more extreme way. Naruto could have received some special training from an unknown source that gives him an edge over Neji. He might also be under the influence of a special power - up item or a curse that enhances his abilities but also makes him more violent. In that case, his strength could easily overpower Neji's skills.
Jealousy could be a reason. Suppose Neji has achieved something that Naruto desperately wants, like a high - ranking position in the village or a special recognition. Naruto's envy could turn into anger and fuel a fight where he overpowers Neji. Another reason could be a misunderstanding. Maybe Neji is wrongly accused of something that Naruto holds dear, like endangering a friend. Naruto, in his haste to protect and seek justice, attacks Neji with full force.
One possible plotline could be that Naruto has a sudden and extreme power-up that makes him overconfident. This overconfidence leads him to challenge Neji in a spar that gets out of hand and he ends up 'destroying' Neji in the sense of completely overpowering him. Maybe Naruto has unlocked a new form of his chakra that Neji can't counter with his Gentle Fist technique.
Yes, there might be such a fanfiction. In the Naruto fandom, with its large and diverse range of fan - created works, various out - of - canon scenarios are explored. However, this goes against the original storyline where Hinata and Neji have a complex relationship that is more about growth, understanding, and family bonds rather than such a violent act.
Naruto and Neji's friendship in fanfiction often delves into their past traumas. Naruto understands Neji's pain of being in a rigid clan structure, and Neji realizes Naruto's loneliness from being an outcast as a child. This mutual understanding cements their friendship. They support each other in battles, with Naruto relying on Neji's strategic mind and Neji depending on Naruto's raw power and determination.
Their relationship could develop from initial distrust to mutual respect. Naruto might be the one to break the ice with his friendly and outgoing nature, while Neji would slowly open up as he sees Naruto's growth and determination.
It could be Sasuke. If he were to turn to the dark side in the fanfiction, his Rinnegan powers could be used to destroy Konoha. He has the potential to be extremely powerful and if he has some sort of vendetta or is influenced by some dark force, he might take his anger out on the village.
One great fem Naruto and Neji fanfiction idea could be set in an alternate universe where they are both on a mission together to save their village from a mysterious new threat. Along the way, they have to learn to trust each other more deeply as they discover new powers within themselves.
I've heard of a fanfic where female Neji has a special connection with Naruto through their shared experiences of being outcasts in a way. Naruto was shunned for having the Nine - Tails, and Neji, in this story as a female, faced different expectations in her clan. Their relationship starts as a mutual understanding and slowly blossoms into something more. It's really interesting to see how the author plays with their characters' emotions and development.