Definitely Sasuke could make an appearance. He could be a mentor figure to Shinachiku, teaching him some of the more advanced and dangerous jutsu. Sakura could also be there as a healer and a strong female role model. And don't forget about Kakashi, who could offer his wisdom and guidance. There could also be some new characters created specifically for the fanfic, like a mysterious outcast ninja who befriends Shinachiku and has some dark secrets related to the past of the ninja world.
Well, obviously Naruto and Hinata as Shinachiku's parents. His friends could be the children of other Naruto characters, like Boruto's friends. Maybe the son or daughter of Shikamaru could be his strategic partner in some adventures. Also, the new generation of the Akatsuki could be potential villains in the fanfic.
In a 'boruto shinachiku world fanfic', potential characters would include Shinachiku's family members for sure. Naruto, being his father, would play an important role. Hinata as his mother would be there to support and guide him. Boruto would be his cool older brother. Besides, characters like Konohamaru, who is now a teacher, could also be in the story. He could train Shinachiku and help him grow as a ninja. Also, the friends that Shinachiku makes on his own adventures, new characters created specifically for the fanfic could be part of it.
Obviously, the other Titans like Robin, Starfire, Cyborg, and Raven would be great characters to include. They could be the students in Beastboy's lessons. Maybe the Doom Patrol members could also make an appearance. They were Beastboy's first team, and they could come in to share their wisdom or add some challenges to Beastboy's teaching. And don't forget about the villains. They could be used as examples of what not to do or as obstacles that the Titans need to overcome using what Beastboy has taught them.
Obviously, Kurenai herself could be a central character in the harem. Also, Anko could be a potential member as she is associated with Kurenai and has her own unique personality. Hinata might also be involved as she has a crush on Naruto and could be drawn into this situation due to her connection with Naruto and the overall Naruto - Kurenai scenario.
Kakashi could be a potential swordsman character. He's known for his combat skills. In the harem, Hinata could be there. Her gentle nature would contrast with the action-packed world. Also, Ino could be part of it, using her mind - control jutsu in unique ways to protect the group and be involved in the harem's relationships.
Naruto himself could also be a main character. He could visit the Hidden Star Village and interact with the Hoshikage, getting involved in the village's affairs and helping them solve their problems. This would be an interesting way to incorporate the Naruto we all know into the fanfic.
Well, obviously Naruto and Konan are the main ones. But other characters like Sakura could be part of it. Sakura, being a strong - willed and skilled kunoichi, might be attracted to Naruto's growth and his new - found status in the ninja world. Hinata could also be included. Her long - standing love for Naruto could easily fit into the harem concept, and she could interact with Konan in an interesting way.
He could meet Konan. Konan is closely associated with the Hidden Rain Village. Her paper - based jutsu would be an interesting interaction for Naruto. Maybe she could teach him something about her unique style of combat or they could end up in a battle.
Sakura could be one. She's a skilled ninja and also Naruto's friend. She would likely use her medical ninjutsu knowledge to see if there are any physical or chakra - related reasons for Naruto's transformation and try to reverse it. Another one could be Kakashi. He has a lot of experience and knowledge. He might research in the old ninja scrolls to find a solution.
It's possible that a group of students could be the main characters. They all learn from the genius sensei in different ways. One student might be great at physical combat, another at ninjutsu, and they have to work together under the sensei's guidance. Their combined growth and how they interact with each other and the sensei can form the core of the 'naruto genius sensei fanfic'.
A new Akatsuki member, a young and powerful ninja who has a personal vendetta against Naruto. Their clashes could add a lot of drama and action to the fanfic.