Naruto's reaction could be complex. On one hand, he would be happy to find someone else from his clan. He has always been proud of his Uzumaki heritage despite not knowing much about it at first. But on the other hand, he might be a bit cautious. Karin has been associated with some not - so - good groups in the past. However, overall, his positive nature would probably lead him to approach Karin with an open mind and try to build a connection with her based on their shared Uzumaki roots.
One implication could be that it strengthens the Uzumaki presence in the story. With Naruto already being a prominent Uzumaki, Karin's addition means there are more Uzumaki characters around. It could also mean that they might have some special abilities or powers related to their clan that could play a role in future events. For example, their strong life force which is characteristic of the Uzumaki clan.
A fanfiction could start with Naruto and Karin being forced to team up due to a prophecy. At first, they clash because of their different personalities. Naruto is all about friendship and believing in people, while Karin is more cautious and self - centered. But as they face stronger enemies, they start to see the value in each other.
One great Naruto and Karin Uzumaki fanfiction could be about their journey together to discover a new jutsu. They might start as reluctant partners but gradually grow to respect each other's skills.
Once Naruto finds out about the Uzumaki clan in the fanfiction, it could change his relationships. He may become closer to certain characters who have a connection to the Uzumaki. For instance, if there are other characters with Uzumaki blood, they might form a special bond. Also, this discovery could influence how the village views him. Some might see him as an even greater asset now that they know he has such a powerful clan background, while others might be more wary of his potential.
Sasuke might be initially shocked. He has always seen Naruto as a rival and suddenly finding out Naruto is a girl could completely change his perception. He may start to view Naruto in a more protective way, as his traditional views of gender roles might make him feel the need to safeguard her now that he knows she's female.
Karin could potentially develop a new form of sensing. Since Naruto has such a powerful and distinct chakra signature, it could inspire her sensory abilities to evolve. She might be able to sense not just the presence of people but also their intentions from a greater distance. This would make her an even more valuable asset in missions.
In the realm of fanfiction, almost any scenario is possible. Regarding Sasuke divorcing Sakura for Karin, it may exist. Fanfiction authors draw inspiration from the source material and then take it in new directions. The idea might stem from Karin's past feelings for Sasuke and some fans' desire to see how such a relationship shift would impact the characters. It could also be a way to explore the characters' personalities more deeply, for example, how Sakura would cope with such a betrayal and how Karin would handle being with Sasuke in that context.
Yes, there are likely some fanfictions out there where Sasuke marries Karin. You can try searching on popular fanfiction websites like FanFiction.net or Archive of Our Own (AO3).
There probably is. Fanfiction writers like to take existing characters and create different storylines. But it's important to note that this isn't part of the official Naruto story. In the original, Sasuke and Sakura are a couple, and Karin has her own relationship with Sasuke which is more of comradeship in the official plot. Fanfiction just gives people the freedom to deviate from the original.