If Kurenai became Naruto's sensei in fanfiction, Naruto might learn some unique jutsu related to genjutsu. Kurenai is a genjutsu expert, and she could potentially teach Naruto how to use genjutsu more effectively or even develop his own genjutsu - based attacks. This could add a whole new dimension to Naruto's fighting style.
Well, perhaps in the fanfiction, Naruto being Kurenai's sensei could lead to him teaching her some unorthodox methods. Since Naruto has his own way of doing things, he might introduce her to new ways of fighting or thinking that completely revolutionize her ninja skills. This could create interesting storylines where Kurenai has to adapt to Naruto's teaching style while still holding on to her own values.
Their relationship could start off rocky as Kurenai might be hesitant to accept Naruto as her sensei. After all, Naruto is younger and has a very different style. But as time goes on, she would start to see the value in his teachings.
Naruto would support Kurenai by being her emotional pillar. He has a very empathetic nature, so he would listen to her concerns about the pregnancy, like her fears for the baby's health or how she's going to be a mother. He would offer words of encouragement and tell her she's going to be a great mom.
Kurenai's teaching style as Naruto's sensei would likely be more focused on genjutsu compared to Kakashi. Kakashi was more about overall combat skills and strategy. Kurenai would probably drill Naruto in the subtleties of genjutsu, like how to create more complex illusions and how to break through an opponent's genjutsu faster.
Tenten could be one of the characters. She could be Naruto's friend and also have a bit of a crush on him. Ino might also be present, using her mind - related jutsu to try and understand the complex relationships in the harem. Rock Lee could show up too, providing some comical relief and also being Naruto's loyal friend in the midst of all the relationship chaos.
In the fanfiction, Naruto's new sensei could be a mysterious figure who has ties to the Sage of Six Paths. This person might have been waiting for the right time to appear and train Naruto. They could possess knowledge about the origin of chakra and how to fully unlock Naruto's power. It could also be someone who was once an enemy but has now changed their ways and wants to use their skills to train Naruto for the greater good of the ninja world.
There's a chance that Naruto's new sensei could be a self - taught ninja who has developed their own unorthodox style. This person sees Naruto's ability to think outside the box and wants to refine that in him. They could introduce Naruto to a new way of looking at chakra control and combat strategies that are completely different from what he has been taught so far.
I think Orochimaru would be the most unexpected sensei. Usually, he's seen as a villain, but in a fanfiction, if he were to train Naruto, it would be extremely unexpected. He has a vast knowledge of jutsu, especially forbidden ones. He could teach Naruto some very powerful and unique abilities, but at the same time, Naruto would have to deal with Orochimaru's morally ambiguous nature.
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.