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.
It could be a special chakra boost. Since Kyuubi has a vast amount of chakra, it might gift Naruto with an extra dose of chakra that is different from what he already has. This could help Naruto in a difficult battle or in achieving a new jutsu.
Naruto would become much more powerful. The Sharingan could give him an edge in battles, allowing him to copy jutsu more easily. He might be able to use it to analyze his opponents faster. However, he would also have to deal with the negative aspects of the Sharingan, such as the potential strain on his eyes and the risk of overusing it.
A simple plot could be that Itachi entrusts Naruto with his Sharingan because he believes Naruto can use it to bring peace to the ninja world. Naruto, being the kind - hearted person he is, accepts the responsibility. He starts training with Kakashi to understand and master the Sharingan's powers. With the Sharingan, Naruto can anticipate his opponents' moves better and uses this advantage in battles against powerful enemies like Pain.
One possible thing that could happen is Naruto would gain new visual abilities. With the Sharingan, he might be able to copy jutsus even more effectively than before. The Sharingan could also potentially enhance his perception of his opponents' moves, making him an even more formidable fighter in battle. This could change the power dynamics in the Naruto universe significantly.
Well, in this fanfiction, Madara could give Naruto the Sharingan as a way to balance the power in the ninja world. Naruto then uses the Sharingan's ability to predict movements in combat. This gives him an edge against enemies who are used to his regular fighting style. He might also discover some hidden abilities of the Sharingan that no one else knew. For example, it could have a unique connection to his Nine - Tails chakra, creating a whole new set of jutsus.
One potential implication is that Naruto would gain enhanced visual abilities. The Sharingan can copy jutsu and see through illusions, so Naruto would be even more powerful in combat. For example, he could quickly learn new enemy techniques during battles.
One plot implication could be that Naruto becomes an outcast among some in the village who fear the power of the Sharingan. This would create internal conflict within Konoha. Another is that Naruto might be targeted by enemies who want to either steal the Sharingan or kill him to prevent him from becoming too powerful. Also, it could change his relationship with Sasuke, as they both now share a connection to the Sharingan.
One possible plotline could be Naruto suddenly gaining the Sharingan through some mysterious jutsu accident. With the Sharingan, he could quickly learn new techniques and have enhanced perception. Combined with the Kyuubi's power, he might become an almost unbeatable force. For example, he could use the Sharingan to better control the Kyuubi's chakra flow, making his attacks more precise and powerful.
It's not an extremely common theme. While the Naruto fanfiction world is vast and diverse, the idea of the female Kyuubi giving birth to Naruto is quite out - of - the - box. Most fanfictions tend to focus on more traditional relationships like Naruto's growth, his friendships, or his romances. However, there are always some creative and unique fanfictions that explore such unusual concepts, but they are a niche within the larger fanfiction community.