Well, one possibility is that he'd have the Sharingan from the start. He might grow up with different training methods, more focused on Uchiha techniques. Maybe he'd be more of an outcast in the village not just because of the Nine - Tails, but also because of the Uchiha's reputation. And his relationship with Sasuke would be completely different, perhaps they'd be rivals in a whole new way, competing over who is the true Uchiha heir in terms of power and abilities.
Perhaps in this fanfiction, Naruto being born an Uchiha means he has a natural rivalry with Sasuke from the start. Since they both have Uchiha blood, they might compete not just for power but also for the right to be the true heir of the Uchiha legacy. Also, his Uchiha lineage could attract the attention of Orochimaru, who might see Naruto as a new vessel with the potential of the Uchiha powers.
Well, if Naruto was born into the Uchiha clan in a fanfiction. His entire backstory would be rewritten. For one, he'd be part of a clan that had a tragic history even before the events of the main Naruto story. He would have access to the Uchiha library and knowledge, which could make him a much more knowledgeable ninja at a younger age. In terms of his fighting style, he'd probably incorporate more Uchiha - style jutsu. His relationship with Kakashi would be different. Since Kakashi had a connection to the Uchiha through Obito, there could be a more complex dynamic. Also, Naruto's role in the Uchiha massacre plot could be completely different. Maybe he could even prevent it, given his different perspective and abilities.
If Naruto were born an Uchiha, his relationship with Sakura might be affected. Sakura might be more drawn to him initially because of the allure of the Uchiha clan. However, Naruto might be more focused on restoring the Uchiha name and proving that they are not all bad. His relationship with the villagers would be complex. Some would be fearful, while others might hope that he could use his Uchiha powers for the good of the village.
The relationships in the story would be different. In the original, Naruto had a complex relationship with Sasuke, who was an Uchiha. But if she was an Uchiha herself, that dynamic would be completely altered. They could be more like siblings or rivals within the clan. Also, her relationship with Kakashi would be different as he had his own history with the Uchiha.
If Naruto was born in the Uchiha clan in fanfiction, he would surely have the Sharingan. This powerful eye technique would give him enhanced perception, allowing him to copy other ninja's moves more easily. He could also use Genjutsu more effectively. Along with that, he might still have some connection to the Nine - Tails, but it could be more subdued or combined with his Uchiha powers in a unique way. Maybe he could use the Nine - Tails' chakra to boost his Sharingan abilities, like increasing the power of his Amaterasu if he were to unlock it.
He might be more reserved. The Uchiha are often seen as a more introverted clan, so Naruto could be less of the loud and boisterous character we know. Instead, he might be more brooding and focused on inner power and self - discovery.
One common plot element is the early access to the Sharingan. Since Naruto is born an Uchiha, he usually gets the Sharingan much earlier than in the original series. Another is the change in his relationships. His bond with Sasuke becomes different as they are now clan - mates. Also, he often has to deal with the Uchiha clan's secrets and history, which was a big part of Sasuke's story in the original but now becomes Naruto's too.
In a fanfiction, an OC Uchiha born with an activated Sharingan could face unique challenges. The Sharingan drains chakra, and being born with it activated might mean they have to learn early on how to manage their chakra levels more effectively. Also, they could attract unwanted attention, either from jealous clan members or from enemies who see them as a threat due to their special ability.
A plot twist could also involve her relationship with the other Uchiha members. Since Naruto is known for her strong will and determination, she might challenge the traditional Uchiha ways. For example, the Uchiha are often associated with revenge and a thirst for power. But she could try to change that mindset within the clan, causing a rift between those who want to stick to the old ways and those who are inspired by her new ideas.