Well, in a fanfic where adult Naruto meets kid Naruto, it could be really interesting. Adult Naruto might be super proud of his younger self. He could give kid Naruto some tips on how to train better and how to deal with the loneliness he sometimes feels. Maybe he'd also tell him some spoilers about future events in a fun, teasing way.
Well, in such a fanfiction, Naruto might learn some new and cool ninja techniques from the toads. Maybe he'll have an adventure in the toad village and make new friends among the toads.
One possible relationship could be that of a student and teacher. Naruto could learn from the toads like he does from his human sensei. Another relationship might be friendship. They could become friends and support each other in different situations.
In a fanfiction where Boruto meets Kid Naruto, there could be a lot of chaos at first. Boruto might be shocked to see a younger version of his father. Kid Naruto would probably be curious about Boruto's strange clothes and gadgets. They could end up getting into some kind of adventure together, like facing a common enemy. Maybe Boruto would show Kid Naruto some of his ninja techniques from the future, and Kid Naruto would teach Boruto some of his own unique skills that he developed during his own time as a young ninja.
It could be the First Hokage, Hashirama. Naruto would be amazed by his powerful Wood - Style jutsu and his ability to create the village. He could learn about the original ideals behind the Hidden Leaf from Hashirama.
Teamwork is also a big theme. Despite being the same person in essence, the two Narutos often have to learn to work together. This can be challenging as they may have different personalities due to their different experiences. For example, one Naruto might be more cautious while the other is more impulsive. And the theme of friendship also plays a role, as they are, in a way, their own best friends in these stories.
Perhaps the kid is from a foreign land that Naruto visited during one of his missions. The kid could be an outcast in his own place because of some unique trait. Naruto, being the kind - hearted person he is, decides to adopt him. It could be that the kid has a different kind of chakra or a strange mark on his body that makes others afraid of him, but Naruto doesn't care.
Well, it could be that Naruto meets the Hokage in a different time - space. They might work together to change some important events in the history of the village. For example, preventing a great disaster or changing the fate of some important characters. And Naruto could learn a great deal from the Hokage's wisdom and leadership in this encounter.
One interesting plot could be two Narutos from different timelines meeting. They could exchange stories about their battles and growth, and then team up to face a new, powerful enemy that neither could defeat alone.
Well, obviously Naruto himself would be the main character. There could also be his friends like Sasuke and Sakura, who might be involved in the interactions between the two Narutos. Maybe they are confused at first by seeing two Narutos, but then they help them figure out what's going on.