One interesting plot could be Naruto fully transforming into the Nine - Tailed Fox during a battle against a powerful enemy. His friends are initially shocked but then try to find a way to bring him back to his senses.
In some fanfictions, Naruto might turn into the Nine - Tailed Fox due to a dark curse. The story could then revolve around his journey to break the curse while dealing with the new - found power and the fear it instills in others. He might have to face his inner demons as well as external threats. For example, the Hidden Villages might see him as a threat and try to stop him, while his friends like Sasuke and Sakura are conflicted between protecting him and protecting the world from him.
One interesting plot could be Naruto's struggle to control the power of the Nine - Tailed Fox when he releases it. He might have to face inner demons and the fear of losing himself to the fox's power.
In this type of fanfiction, often Naruto's transformation into the nine - tailed fox can lead to some really cool battle scenes. He could use the fox's speed and strength in unique ways. Like, he might be able to run up walls or jump extremely high to attack enemies from unexpected angles. Also, there could be a plot where Naruto has to enter a sort of spiritual realm within himself to communicate with the nine - tailed fox and gain better control over their combined form.
One possible plot twist could be that Naruto loses control over his transformation into the Nine - Tailed Fox in a completely unexpected situation. Maybe during a friendly spar with his friends, and this causes them to fear him in a new way. It would add a whole new layer of drama to their relationships.
Well, if Naruto turns into the nine - tailed fox in a fanfic, it would be really cool. He would likely be almost uncontrollable at first, as the power of the nine - tailed fox is so immense. But as the story progresses, he could learn to harness that power. His friends might be both in awe and a bit scared of him. And he could use the nine - tailed fox's abilities like its tails for attacks and its natural cunning in combat situations.
One interesting fanfiction could be about the Nine - Tailed Fox's origin before it was sealed in Naruto. Maybe it was a powerful and free - spirited being in a different realm, and the story could explore its relationships with other mythical creatures there.
One idea could be exploring the relationship between Naruto and the Nine - Tailed Fox in more depth. Maybe Naruto has to enter the fox's mind - scape and they have a long conversation about their fates being intertwined. Another plot could be a 'what if' scenario where the Nine - Tailed Fox was released earlier in Naruto's life and how he would deal with it without as much training. A third idea is to have the Nine - Tailed Fox take on a human form and accompany Naruto on his adventures, causing all sorts of chaos and also some unexpected moments of friendship.
His relationship with the villagers could become more complex. Some might see him as a greater threat, while others who have come to know Naruto as a hero might be more accepting. His transformation could also lead to new alliances as some might want to use his power for their own purposes, which Naruto would have to navigate carefully to protect his relationships.
Obviously Naruto himself, as he is the one turning into the Nine - Tailed Fox. Sasuke would also likely be involved. He might be the one to try and reach Naruto when he is in his fox - form, either to fight him or to bring him back. Sakura too, she could use her medical ninjutsu to try and help Naruto if he gets injured during the transformation.
It could make his friends more cautious around him. For example, Sakura might be a bit more hesitant to get close, fearing the power of the Nine - Tailed Fox. But at the same time, some like Sasuke might see it as an opportunity to become stronger by sparring with Naruto in this new form.
One idea could be exploring the relationship between Naruto and the Nine - Tailed Fox in more depth. Maybe showing how they communicate on a deeper level, not just when Naruto is using its power.