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.
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.
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.
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.
I haven't actually read this specific fanfic, but generally, in fanfics that pair characters like Deidara and Sakura, it could explore an alternative universe where their paths cross in unexpected ways. Maybe it delves into their different personalities and how they interact, with Sakura's strong - willed nature contrasting with Deidara's explosive art - based ideology.
I'm not sure if there is a specific 'sakura x akatsuki lemon fanfic' available. You could try searching on some popular fanfic websites like Archive of Our Own or Fanfiction.net.
I'm not sure specifically as it depends on the particular fanfic. It could be about a situation where Karin is shown bullying Sakura within the context of the fan - created story.
Maybe Karin has some personal reasons. For example, she might not like Sakura's character in the original work, so she also dislikes fanfic related to Sakura.
I'm not very familiar with this specific 'isshin x karin lemon fanfiction'. However, generally in fanfiction, the 'x' usually indicates a romantic or pairing relationship. It might explore the relationship between Isshin and Karin in an interesting way. Maybe it has unique characterizations and plot developments centered around their relationship.
It's hard to say who the best are as it's quite subjective. But some authors who have a large following and are well - known for their Karin and Sakura lemon fanfictions are those who really capture the essence of the characters. They might be the ones who write very detailed descriptions of the characters' emotions and actions.