Obviously Naruto himself is a central character. Sasuke is also very common as he was an important part of Naruto's childhood, being his rival. Sakura is often included too, as she was part of their team. And of course, Iruka - sensei, who was like a father figure to Naruto in his early days.
One interesting aspect could be the exploration of Naruto's relationship with his friends in childhood. For example, how his bond with Sasuke started to form. It might also show his training with Iruka - sensei in more detail, like the challenges he faced and how he overcame them.
In a fanfic, Naruto might talk about how lonely his childhood was at first. He could mention being shunned by the villagers due to the Nine - Tails inside him. For example, he might recall how the other kids were not allowed to play with him, and he often had to eat alone. This sense of isolation was a big part of his early years.
There's 'Naruto and Sasuke: Childhood Memories'. This fanfic focuses on their emotional bond. It details how they supported each other during tough times in the village. For example, when Naruto was being shunned by some villagers, Sasuke was there for him, and vice versa. It's a heartwarming read that really showcases their friendship.
Naruto would probably describe his relationship with Iruka - sensei as very special. Iruka was like a father figure to him. He might say that Iruka was the first to believe in him and give him the recognition he so desperately wanted.
These fanfics are appealing as they allow for a lot of creativity. Writers can take the basic framework of Naruto and Sasuke's childhood friendship and expand on it in various ways. They can add in new characters or events that enhance the story. Also, it gives fans a sense of nostalgia as they remember the early days of the Naruto series and the simple yet powerful bond between these two iconic characters.
The appeal lies in the contrast of their personalities. Naruto is loud and outgoing, while Sasuke is more reserved. In a fanfic, seeing how these two opposite personalities become friends is interesting. For example, Naruto might drag Sasuke into his crazy adventures, and Sasuke would reluctantly go along but end up having fun.
There's also 'Childhood Memories'. In this fanfic, the author focuses on the small, often overlooked moments between Naruto and Sasuke as children. It's a short but sweet read that gives you a warm feeling about their friendship. It shows how their different personalities complemented each other even at a young age.
Often, there are scenes where they train together as kids. Naruto, with his boisterous energy, tries to encourage Hinata, who is initially more reserved. They share a moment of mutual respect and friendship during these training sessions. For example, Naruto might praise Hinata for a new jutsu she's learned, which boosts her confidence and strengthens their bond.
There's also 'Naruto's Childhood Adventures'. This fanfic delves into Naruto's pranks around the village as a child. It's a fun read as it shows his mischievous side, which was also a way for him to get attention in his own way. It has some really heartwarming moments when the villagers start to see him in a different light.