If Naruto is sealed in his younger self in a fanfic, the story development would be full of surprises. His relationship with Kakashi Sensei could start much earlier and be more intense. Since he has the essence of his future self, he might be able to figure out some of Kakashi's secrets sooner. In battles, he could use tactics that are way beyond his supposed level of experience. This could make him a target for stronger enemies at an earlier stage. And as for his personal growth, he would have to balance his young self's naivete with the knowledge and power of his future self.
The story could develop in many ways. For one, Naruto's friends might notice his sudden change in behavior. He might seem more mature or have knowledge that he shouldn't have at his young age. This could lead to some interesting conversations and misunderstandings. Also, the ninja academy days could be completely different. He could potentially skip some levels of training or teach his classmates new techniques. The story could also focus on how he tries to keep his sealed self a secret from those who might try to take advantage of it.
If Naruto is sealed in his younger self in a fanfic, it could be chaotic. His chakra control might go haywire as his younger body tries to adapt to the sealed future self. The village elders might notice something strange and try to investigate. His training with Iruka Sensei could take a whole new turn as he might show advanced skills too early. This could also have an impact on the Nine - Tails within him. The Nine - Tails might react differently to this new situation, perhaps becoming more or less aggressive depending on how the seal affects Naruto's mental state.
Well, Naruto might try to give his younger self some advice. Maybe he'd tell him to train harder or to be more understanding of Sasuke earlier. It could be a really interesting scenario where the older Naruto tries to prevent some of the bad things that happened in his past from occurring again.
In this fanfic, Naruto might use his time - traveling jutsu accidentally. He could then see his younger self in a dangerous situation, like being attacked by a powerful enemy. So, he jumps in to save him, using all his advanced skills and knowledge. Maybe he also gives some important advice to his younger self to avoid future mistakes.
In fanfiction, this concept would have a huge impact. Naruto's growth would be different. He would have to deal with the power of the Juubi at a time when he is still developing his own identity. This could lead to a different Naruto, one who is more mature in some ways and yet still retains his naivete in others. The story could also explore how the village and its people react to this new Naruto. Some might fear him, while others might see him as a new hope. And in battles, Naruto could potentially defeat enemies much quicker, which would change the overall plot of the Naruto universe in fanfiction.
In this kind of fanfiction, it could lead to some really interesting power dynamics. Naruto might gain new abilities or have a different understanding of his powers at a younger age. Maybe he could use the power of the Juubi to protect the village in ways he couldn't before in the original story.
The story might progress with the older Naruto taking the younger one on special training missions. They could go to places that the younger Naruto has never been before, like some hidden training grounds in the outskirts of Konoha.
One possible thing that could happen is that Naruto could teach his younger self some advanced jutsu. For example, he might show the younger Naruto how to better control the Nine - Tails' chakra earlier. This would give the younger Naruto a significant power boost and change the way he approaches battles in his early days.
Maybe Kabuto. He's a sly character who often works for the more powerful villains. He could be sent to capture Naruto's younger self for some experiment or to gain information. Naruto would need to fight against Kabuto's medical ninjutsu and his sneaky tactics to save his younger self.
If Harry Potter is sealed in Naruto fanfiction, the story might start with Harry being confused and disoriented in this new world. He'd soon discover that his magic works differently here. As he tries to find a way back home, he could get involved in the conflicts between the ninja villages. His magic could be a game - changer in some of the battles, and he could become a key figure in the power struggle, either as a feared opponent or a valuable ally depending on which side he chooses.
Well, it could have a huge impact. Naruto, being more experienced, can teach his younger self new jutsus. He might also instill in him a stronger sense of self - belief. For example, he could show his younger self how to better control the chakra of the Nine - Tails. This would make his younger self more confident in battle and in dealing with the village's expectations.