There could be characters related to Luna. Maybe Luna has some friends or family members who play important roles. Also, the regular Naruto characters like Sasuke and Sakura would still be there, but their relationships with Naruto might change due to his new identity as Luna's son.
In this 'naruto son of luna fanfiction', aside from Naruto, we could expect to see Luna's allies. They could be some sort of magical or otherworldly beings that have their own unique abilities. Then there are the antagonists. There might be those who oppose Luna and by extension, Naruto. Also, the senseis in Konoha like Kakashi and Iruka would still be important characters. Their guidance to Naruto could be even more crucial as he navigates this new aspect of his identity. And we might also see new characters introduced from the world or story related to Luna, which could add more depth and complexity to the fanfiction.
Potential characters could include Luna herself, of course. She might be a powerful being from a different realm or a hidden part of the Naruto universe. There could also be other characters who are protectors or enemies of Luna. And don't forget the other ninja clans in Konoha. They might react differently to Naruto once they find out he's the son of Luna. Some might be suspicious, while others might see it as an opportunity for Konoha.