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.
The Sharingan and Rinnegan are iconic in Naruto fanfic. The Sharingan's different levels, from one - tomoe to three - tomoe and then the Mangekyou Sharingan, offer a wide range of creative possibilities. Fanfic writers might explore the emotional toll of using the Mangekyou Sharingan, like Itachi did. Regarding the Rinnegan, it's often associated with the Sage of Six Paths. In fanfic, it could be used to bring back ancient powers or create new forms of ninjutsu. These two eye - powers can be combined in fanfic in ways that the original series might not have fully explored, making for exciting reading.
Yes, in some fanfictions, Naruto can be depicted as having the Sharingan. Fanfiction writers often like to play with different character abilities and combinations, so it's not uncommon to see Naruto with the Sharingan in their creative works.
The Sharingan in such a fanfiction could be used as a tool for a Fairy Tail character to gain an edge in their battles. They might initially struggle to control it, but as they learn more about it, they become a formidable force. For instance, they could use the Sharingan's genjutsu abilities to deceive opponents in the Fairy Tail battles.
In some fan theories, it could be due to a unique chakra interaction. Maybe the Kyuubi's powerful chakra somehow mutates Naruto's own ocular abilities and triggers the emergence of the Sharingan. But this is just a wild fanfiction idea.
In some fanfictions, it could be due to a special jutsu gone wrong. Maybe a jutsu that Kakashi was using to transfer some of his chakra to Naruto for a mission accidentally transferred his Sharingan power as well.
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.
Maybe by creating false visual illusions. For example, using some basic ninja techniques like the Transformation Jutsu to disguise as someone important to the Sharingan user. This could make the Sharingan user misjudge the situation and fall into the trap.
In a fanfic where Danzo gives Naruto the Sharingan, it could lead to a very different Naruto. Naruto might gain new abilities and a new perspective on the Uchiha. He could potentially master the Sharingan quickly with his strong willpower, but he would also have to deal with the dark side of the Sharingan, like the curse of hatred that often comes with it.