Well, there could be an old butler who has been in the household for decades. He initially doubts Naruto's abilities but later becomes his mentor. And then there could be a group of thieves who target the wealthy household. Naruto has to use his butler skills and ninja skills to fend them off. And perhaps a childhood friend of Naruto's who visits him at the butler job and is amazed at how he has changed.
Sakura could be a main character. She could be the one who encourages Naruto to get into dance in the first place. Maybe she has a secret love for dance and wants to share it with Naruto. She could also use her medical ninjutsu knowledge to help prevent dance - related injuries within the group.
Well, obviously his sister would be a main character. She could be someone with a very different personality from Naruto. Maybe she's more introverted and focused on her studies or training in a very solitary way. Another character could be Naruto's mentor, like Iruka. He might be one of the few people who actually notice Naruto's struggle of being ignored because of his sister, and try to encourage Naruto in his own way.
Sasuke could be one of the main characters. He might initially be skeptical about Naruto's plan to rebuild Revan's army but later come around and offer his skills. Another could be Kakashi. His experience and wisdom would be valuable in guiding the new recruits. Sakura too, with her medical skills, could play an important role in taking care of the army members during battles and training.
Sasuke could be a great main character in such a fanfiction. He has a deep connection with Naruto. If Naruto's dying will flame is involved, Sasuke might be on a journey to understand what Naruto left behind and how to carry on his legacy. He could be conflicted between his own past and the new responsibility that comes with the dying will flame.
Boruto is often a popular character in such fanfiction. Since he also has the Jougan, stories might focus on his training with Naruto to master this power. Their father - son relationship can be explored in new ways as they both deal with the implications of the Jougan.
One possible plot could be that Naruto is sent to a different dimension where he has to work as a butler to support himself. He uses his ninja skills in a unique way, like using his speed to serve food quickly and his stealth to eavesdrop on important conversations among the household members, which later helps him solve some mystery in the big manor he works in.
Sakura could be one. Since she's very intelligent and has strong medical skills, she could help in the process. Maybe she'd be in charge of the clan's medical and research aspects related to the Senju bloodline.
Sakura could be one. She has always had a bit of a complex relationship with Naruto. In this harem fanfiction, she might see Naruto in a new light and become part of the harem. Another could be Hinata. Given her long - standing crush on Naruto, it would make sense for her to be in the story. Also, Tenten. She's a strong and independent ninja, and her interaction with Naruto could be an interesting addition to the harem scenario.
Hermione would surely be there. She might be a fellow professor, teaching a subject like Transfiguration or Ancient Runes. She could be Harry's confidante and help him with academic matters at Hogwarts. Also, Ron could make an appearance, perhaps as a visiting lecturer from time to time, sharing his knowledge of wizarding chess and other aspects of wizard culture.
Definitely the Kumo ninjas who carry out the kidnapping. There could be some well - known Kumo characters like Killer Bee. He might be involved either directly in the kidnapping (unlikely as he is more of a good guy in the original) or in the events that follow. Another character could be the Raikage. He may or may not be aware of the kidnapping depending on the plot. If he is aware, his actions and decisions would play a major role in how the story unfolds.