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.
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.
In this fanfic, Naruto might teach his younger self some advanced jutsu. For example, he could show the younger Naruto how to better control the chakra for Rasengan at an earlier stage. This would make the younger Naruto stronger faster in the story.
In this kind of fanfiction scenario, Naruto could potentially change a lot of things. He might use his knowledge of future events to prevent certain tragedies. For example, he could try to save his parents or prevent the destruction of the village by Orochimaru earlier. He could also train his younger self more effectively, sharing all the skills he has learned over the years.
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.
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.
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.
If Kaguya is sealed in Naruto in a fanfic, Naruto could potentially use Kaguya's power for good. He might be able to access new jutsu or abilities that were previously unknown. However, there would also be risks. The power could be corrupting, like it was for Madara when he got some of Kaguya's power. Naruto would have to rely on his strong will and the support of his friends to keep from being consumed by it. He could also try to study Kaguya's power to find a way to break the cycle of hatred that has been plaguing the ninja world for so long.
Well, Naruto could also mentor his younger self about the importance of friendship. He's had so many experiences with his friends like Sasuke and Sakura. He might tell his younger self not to take their relationships for granted and how they all contribute to his growth as a ninja.
In a fanfiction scenario where Naruto meets his younger self, it would be a very unique situation. Naruto might show his younger self some of the new jutsus he's mastered, like the Rasengan variations. His younger self would be eager to learn from him. Also, Naruto could talk to his younger self about his dreams and how he's still holding on to them, even after all the difficulties. This meeting could potentially change the course of his younger self's life, as he could be more determined to reach his goals faster with the knowledge of his future self.
One aspect could be Naruto training his younger self to be a better shinobi. He'd share his battle experiences, like the fights against Haku and Zabuza. His younger self would learn from his future self's strategies and become a more formidable ninja at a younger age. Also, Naruto could help his younger self understand the power of the Nine - Tails in a more positive way, instead of just seeing it as a curse. This could lead to his younger self being more confident and in control of his abilities much sooner.