Itachi is also a popular choice. Even though he was initially portrayed as a complex character with his own moral code in the original series, fanfiction writers might explore a scenario where he fully embraces the 'evil' side of the Sharingan. This could involve him using it for more malevolent purposes than what was shown in the anime or manga, perhaps using it to manipulate events on a grander scale for his own ends.
Madara Uchiha is another character that features prominently. He was already a powerful and somewhat villainous character in the Naruto story. In fanfiction about the evil Sharingan, he can be further developed as an even more menacing figure, with his Sharingan abilities being enhanced or corrupted in ways that create new and terrifying storylines. For example, his use of the Sharingan to control the Nine - Tailed Fox could be expanded upon in more sinister ways.
Itachi also features prominently. His powerful Sharingan and his complex character make him a favorite for fanfiction writers. They might write about his past and how his Sharingan abilities influenced his actions in ways not fully explored in the original series.
Sasuke is often a popular character in such fanfictions. Since he already has the Sharingan in the original Naruto series, it's easy to expand on his powers and make him even more powerful with a godlike Sharingan. Fans love to see how he would handle this new level of power and how it would change his relationships with other characters.
Sasuke is often very popular. His Sharingan abilities are quite powerful and his brooding personality makes for interesting crossovers. Writers can put him in different situations where he has to use his Sharingan in new ways.
Sasuke is often a very popular character in such fanfiction. His original connection to the Sharingan in the Naruto series makes him a natural fit for stories centered around the Mangekyou Sharingan. Another popular character could be Itachi, as his use of the Mangekyou Sharingan was quite significant in the original story, and fanfiction writers like to explore more of his untold stories or alternate scenarios.
Sasuke is often a popular character in such fanfictions. His natural Sharingan abilities make it interesting to explore how he would interact with the Rinnegan powers. Fans like to write about him achieving new levels of power by combining or evolving his Sharingan in relation to the Rinnegan.
Madara Uchiha is another popular character in Naruto Rinne Sharingan fanfiction. Since he was one of the first characters to be associated with the Rinnegan (a precursor to the Rinne Sharingan in some ways), fans are interested in seeing how his character would be even more powerful or how his motives might change if he had the Rinne Sharingan. There are often stories that revolve around his further rise to power or his redemption with the help of this powerful eye ability.
One common theme is the corruption of power. The Sharingan, being a powerful ability in the Naruto universe, when turned 'evil' can lead to a character's downfall. For example, a character might use the evil Sharingan to gain control over others in a more forceful and unethical way compared to normal ninja tactics. Another theme could be the struggle between good and evil within the user of the evil Sharingan. They might be constantly fighting their inner demons while being influenced by the dark power of the Sharingan.
Itachi Uchiha is also extremely popular. His tragic backstory and his powerful use of the Sharingan make him a prime candidate for fanfic exploration. Writers might create stories that expand on his time in the Akatsuki or his relationship with Sasuke before his death.
Sasuke is often a popular character to be portrayed differently. In 'Naruto Evil Within' fanfiction, he might be even more of an anti - hero or fully embrace the dark side, perhaps being more ruthless in his pursuit of power. He could be shown as having a different relationship with Naruto, more adversarial and less likely to be redeemed.
Sasuke is often a very popular character in Sharingan Crossover Fanfiction. His brooding nature and powerful Sharingan abilities make him a great candidate for crossovers. He can be easily transplanted into other universes and his skills can create interesting storylines. For example, if he were in a crossover with the Matrix, he could use his Sharingan to see through the digital illusions.