Power struggles are also quite common. If they have different abilities or powers in the source material, the fanfiction might explore who is stronger, how they use their powers against each other, and what they can learn from their battles. It could also be about proving one's worth, especially in a world where power and status matter a great deal.
A common theme is competition. Since they are both characters with their own strengths, fanfictions often center around them competing for things like recognition, a certain goal, or the attention of other characters.
In some cases, Karin can be more popular. Her backstory of being associated with Orochimaru and her survival instincts make her an appealing character. Some fans might be drawn to the idea of her as an underdog in the love triangle with Sasuke and Sakura. Also, her sensing abilities and her role in certain plot points in the original series can be explored more deeply in fanfics, which might make her more interesting to some readers than Sakura.
Well, Archive of Our Own (AO3) is also a great source. You can search for 'sakura vs karin' there. You may find stories where their abilities are pitted against each other, or perhaps fictions that delve into their backstories and how that affects their relationship in a competitive sense. It really depends on what kind of story you're interested in.
Well, another place could be Tumblr. There are often fanfiction communities on Tumblr where users share and recommend different stories. Look for tags related to Karin, Sakura, and fanfiction. However, the content there might be a bit more scattered compared to dedicated fanfiction sites. You may need to do some more digging to find exactly what you're looking for.
Often, Sakura is depicted as kind - hearted. She is the one who is more likely to see the good in people. Karin, on the other hand, might be more headstrong. For example, when they face a difficult situation, Sakura will try to find a peaceful solution first, while Karin is ready to jump into action right away.
Another plot could be set in a post - war world. Sakura has built a life for herself as a respected medical ninja, but when Karin shows up, claiming that Sasuke still has feelings for her, a new conflict arises. Sakura decides to prove Karin wrong by showing how much she has grown and how well she can take care of Sasuke. Karin then challenges Sakura to various tests of strength and loyalty, leading to a series of events that put their relationship to the test.
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.
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.