Another option could be Kakashi. Suppose he is banished because of some incident related to his Sharingan. He has so much history and experience, and seeing him outside of the village structure, relying only on his Sharingan and his wits, would make for a great story. He could also have flashbacks to his past experiences with the Sharingan while dealing with the challenges of being banished.
One idea could be that the character with the Sharingan is banished due to false accusations of using its power for evil. He then has to journey alone, facing challenges and learning to control his power in new ways. Maybe he meets a group of outcasts who he befriends and together they fight against the unjust system that banished him.
It could be Sasuke. In many Naruto - related stories, Sasuke has the Sharingan and is often the target of others' tricks or manipulations due to his complex personality and his power.
It could be Sasuke. Since he already has the Sharingan and later acquires the Rinnegan, he has a natural connection to both powerful eyes. A story could focus on his further adventures and how he uses the combined powers of the eyes in different situations.
It might also be Itachi. Imagine a scenario where Itachi's actions before his death somehow lead to his Sharingan being abandoned or lost in a different way than in the original story. This could open up a whole new narrative about his legacy and the impact it has on the Naruto world.
It could be an original character. For instance, a ninja who was wrongly framed for a crime and banished. They would then be the focus as they navigate their new life as an assassin.
Sakura could be an unexpected character to have the Sharingan. It would completely change her character dynamics. She could use it to enhance her medical ninjutsu, seeing the internal body structure more clearly. Also, she could become a more formidable fighter, using Sharingan - based genjutsu to her advantage.
A character who is a hybrid of two different clans, one with the Shikotsumyaku and the other with the Sharingan. This would give them a unique perspective and set of skills, making for an interesting main character.
In fanfiction, Naruto could get the Sharingan through a blood - related connection that is revealed later. For example, it could be discovered that he has some distant Uchiha ancestry that gets activated somehow. Maybe a powerful enemy's attack awakens this dormant Uchiha blood in him, and as a result, he develops the Sharingan. It could also be that a powerful sage or a new character uses their own unique powers to bestow the Sharingan upon Naruto for a specific purpose.
A new character could be created as the main character. This character could be an orphan who discovers they have a single Sharingan eye, and they don't know where it came from. They then embark on a journey to find out about their heritage and the origin of their eye. Along the way, they meet various Naruto characters and learn about the power and responsibility that comes with the Sharingan. They might face challenges from both those who want to steal their eye and those who fear its power.
Maybe Shion had a vision that was misinterpreted. People in the village might think Naruto was a danger based on that, so they banish him.