One plot idea could be that Naruto is turned into a monster during a powerful and dark jutsu gone wrong in a battle. He then has to struggle with his new form while his friends initially fear him but later try to find a way to turn him back. Another could be that an ancient curse is placed on him, turning him into a monster, and as a result, he has to go on a journey to find the source of the curse to break it.
In a fanfiction where Naruto is turned into a monster, a really cool plot could be that Naruto's monster form is actually a manifestation of his repressed emotions and power. He has always been so focused on being accepted and becoming Hokage that he has bottled up a lot of his negative feelings. When he turns into a monster, it's like all those emotions are let loose. His friends first think he has been possessed, but as they investigate, they realize it's a part of Naruto himself. So they start to help him come to terms with his emotions and his new form, which ultimately leads to him having better control over his power in both his normal and monster forms.
Well, perhaps Naruto is turned into a monster by a powerful enemy who wants to use his new form to wreak havoc on the Hidden Leaf Village. Naruto, in his monster form, has enhanced powers but also a loss of control. His friends like Sasuke and Sakura would have to work together to try and reach the Naruto inside the monster. They could try different jutsus to communicate with him or subdue his monster side until they can figure out how to reverse the transformation.
Well, perhaps Natsu turned into a girl could lead to a story where she has to go undercover as a female in an all - female magic group. This would force her to learn about the different culture and magic techniques of women - only groups. Or maybe she gets involved in a beauty contest in the magical world by accident, and her friends from the guild have to help her out while she's in this new form.
One idea could be that Harry has to hide his new werewolf form from his friends at Hogwarts. He might struggle with the monthly transformations and the fear of hurting those he loves. Another could be that he discovers a way to control his werewolf side through some ancient magic that no one else has ever tried.
Maybe in this fanfiction, Naruto as a female could develop a different kind of relationship with Sasuke. Since the dynamic between male - female friends can be distinct from male - male friendships, it could lead to new story arcs and character growth for both of them.
One plot idea could be that Naruto is a celestial being sent to the human world on a mission. He has powers far beyond what normal ninjas possess, like the ability to control the elements on a much larger scale. For example, he could stop a natural disaster by simply willing it. Another idea is that he's a spirit in a human form, and he has to find a way to return to his spirit realm while still protecting the village. This could involve him learning about his true identity through a series of mysterious encounters.
Well, a plot could involve Naruto being initially ostracized in the village because of his deafness. But then, he proves his worth by using his unique perspective. Since he can't hear, he becomes extremely observant of body language. This helps him in battles and also in understanding the true feelings of people around him. He could also form a special bond with a character who is also an outcast, perhaps someone with a disability of their own, and together they change the perception of the village towards those with differences.
A possible plot is that Naruto's blindness is a result of a powerful enemy's attack. This forces him into a new world of darkness, but also reveals hidden powers within him. He could start to see things in a different way, not literally but metaphorically. His new - found understanding could lead him to be a better leader. For instance, he might be able to understand the pain of the oppressed in a more profound way, and thus fight for their rights more vehemently. His blindness could also be a way to bring out the best in his friends, as they rally around him to support and protect him.
Another plot could be that Naruto is adopted by an older ninja who has retired from active duty. This ninja has a lot of wisdom and secrets. Under his guidance, Naruto discovers a new power within himself that was hidden all along.
One idea could be Naruto going back in time and meeting his parents when they were young. He could try to prevent their early deaths or change certain events that led to the hardships in his own life. Another plot could be Naruto ending up in the time of the First Hokage, and learning the original ninja ways that were perhaps lost or changed over time. He might also have to deal with the different political situations of that era.
One interesting plot idea could be that the monster fox has a hidden power that only Naruto can unlock through a special bond. For example, they might discover a new form of chakra that combines Naruto's own and the fox's, giving him an edge in battles against powerful enemies. Another idea is that the fox has a past life and memories that start to surface, leading Naruto on a journey to understand the fox's true origin and how it's connected to the ninja world's history. A third plot idea could be that the fox gets separated from Naruto in a strange dimension, and Naruto has to go on a quest to find and rescue it, facing various challenges along the way.
One idea could be that Naruto discovers a hidden village of monster girls in the Land of Fire. He has to learn to co - exist with them and maybe even team up with some to face a new threat that targets both humans and monster musume.