There could be a Suna ninja who becomes Naruto's mentor. This ninja might have a special skill in using sand and wind chakra together and teaches Naruto how to control his own chakra better in the Suna environment. Another potential character could be a young Suna girl who befriends Naruto and shows him the ropes of living in Suna, like where to find the best oasis for water.
A new character could be a Suna - based medic ninja who discovers Naruto's unique Uzumaki healing abilities. She could be intrigued by Naruto and help him develop his skills further. Additionally, there might be a Suna weaponsmith who creates special tools for Naruto, taking into account his Uzumaki strength and the demands of Suna's environment.
There could be new Suna shinobi that Naruto befriends. For example, a young and talented sand ninja who has a unique jutsu related to the desert environment, like being able to manipulate sandstorms on a small scale. Another potential character could be an elder in Suna who has a lot of knowledge about the village's history and secrets, and who helps Naruto understand his new role in Suna.
There could be some of Dragon's comrades in the revolutionary army who become important figures in Luffy's upbringing. For example, a veteran revolutionary who teaches Luffy about the history of the world and the wrongdoings of the World Government.
Obviously Naruto himself is very popular as he is the main character of the original series and the focus in these fanfictions too. Gaara is also quite popular as he is from Suna. Their interactions are often a big part of the stories.
In this fanfiction, a great plotline could be Naruto's struggle with his identity. He is raised in Suna but has the blood of Konoha in him. He might face discrimination from some Suna villagers who don't fully trust him because he's an outsider. But at the same time, he wants to prove himself to both Suna and Konoha. This internal conflict could drive the story forward and lead to some really interesting character development.
There could be a young prodigy from a small, unknown village who has a natural affinity for the Jinton release. This character could come to the Hidden Leaf Village to learn more about controlling it and end up befriending Naruto and his friends.
One potential new character could be a sage who was there during Kaguya's time and has been in hiding ever since. This sage could have knowledge about the true nature of Kaguya's powers and how Naruto can control and use them properly. He might also be a bit of a trickster, making Naruto go through various trials to prove himself worthy of this knowledge.
Another potential new character could be a fellow lost soul. This character could be from another village or even another dimension. Together with Naruto, they could try to find a way out of the darkness while sharing their different experiences and knowledge.
There could be a mysterious mentor figure who guides Naruto in his secret life. This person might have unique abilities and a deep understanding of the ninja world's secrets. Another potential new character could be a spy from another village who discovers Naruto's secret life and tries to use it to their advantage.
Well, in this fanfiction, we might see some new characters related to the Nine - Tails' origin. Maybe there are other tailed beasts' hosts from a long - lost clan who come to offer their knowledge on handling such a situation. Additionally, there could be a hermit who has been observing Naruto from afar and now steps in to guide him through the difficulties of having a broken seal. And don't forget about the potential dark side characters, like a sorcerer who wants to use Naruto's broken seal to open a portal to a dark dimension.
There could be new ninja from other hidden villages that are introduced when Naruto returns. Maybe a powerful young ninja who wants to test his skills against Naruto. Or perhaps a mysterious sage - like figure who has some connection to Naruto's new power.