Another plot idea is a story of self - sacrifice. For example, in a dangerous situation, Sakura and Karin both want to protect Sasuke. They put aside their differences and work together. And Sasuke realizes the importance of both of them in his life through their selfless actions.
One great 'Sasuke x Karin fanfic' is 'The Red - haired Bond'. It beautifully explores their relationship development. Karin's loyalty to Sasuke is depicted in a very heart - warming way.
One key element is the complex relationship between them. Sasuke's often cold and distant nature contrasted with Karin's more passionate and emotional self. For example, in many fanfics, Karin has to break through Sasuke's emotional barriers.
A possible plot could be a time - travel one. Naruto, Sakura, Ino and Hinata are sent back in time to the era of the First Hokage. They have to adapt to the different ways of the old Konoha while also trying to find a way back to their own time. Along the way, they meet the predecessors of their clans and learn about the origins of their jutsus.
There are fanfics like that. Sasuke might leave Sakura for Karin because of Karin's loyalty. Karin has shown unwavering loyalty to Sasuke throughout the series. She was willing to risk her life for him on multiple occasions. In contrast, Sasuke might think that Sakura's love is more of a childhood crush that she hasn't fully grown out of, and he may be drawn to Karin's more mature and selfless loyalty.
I don't have specific knowledge about the common themes in 'karin x sakura lemon fanfic' as it depends on the creativity of the writers. But friendship or adventure could be possible themes.
Love triangles are a very common theme. Sasuke is often at the center of the attention of both Sakura and Karin, which creates a lot of tension and drama.
Finding 'karin x sakura lemon fanfic' might be a bit tricky. It depends on the popularity of these characters in the fan community. You could also check fan forums related to the source material of these characters. There might be some fans who have written or can recommend such fanfics.
One common theme is friendship. Despite their differences and past conflicts, Naruto, Sakura, and Sasuke are often shown rebuilding their friendship in these fanfics. Another theme is redemption. Sasuke, in particular, often has a journey of redemption where Naruto and Sakura play important roles. Also, love in its various forms, whether it's platonic or romantic, is a common theme as the relationships between the three are explored.
A Sasuke Yandere x Sakura fanfic often explores a rather intense and possessive relationship. In such a fic, Sasuke's yandere traits would likely make him extremely protective of Sakura. He might go to great lengths to keep her all to himself, which could add a lot of drama to the story.
A lot of Sasuke x Sakura romance fanfic focuses on the emotional journey. There are the moments of jealousy, especially when other characters seem interested in either Sasuke or Sakura. The fanfics might also delve into how they communicate or rather struggle to communicate their feelings. Since Sasuke is not the most expressive, it creates a lot of tension and drama that makes the romance aspect more interesting. Some fanfics may also include flashbacks to their early days together in Team 7 to show how their relationship has evolved.