In some fanfictions, Kakashi could be kidnapped by a group of rogue ninjas who are after his Sharingan. They might think that by taking him, they can extract the power of the Sharingan for themselves. There could also be a fanfic where he's kidnapped as part of a plan to draw out Naruto and the other Konoha ninjas, to ambush them when they come to rescue Kakashi.
There could be a fanfiction where Kakashi's daughter discovers a hidden power within her. This power might be related to her family's past and she has to learn to control it while also dealing with the expectations of being Kakashi's daughter. In the story, she could meet new friends and allies who help her on this journey.
Well, there might be a 'Sanji kidnapped' fanfiction where he is kidnapped by a group of bounty hunters who mistake him for someone else. In this story, his crew has to embark on a wild adventure to find and rescue him. They face many challenges along the way, like dealing with other pirates who are also after the bounty on the supposed 'target'. It could be full of action and humor as the Straw Hats try to outwit everyone to get Sanji back.
One interesting Renesmee kidnapped fanfiction could be where the Cullens have to use all their vampire powers and alliances to track her down. It might involve a new vampire clan that has some grudge against the Cullens and decides to take Renesmee as a way to get back at them.
One popular 'Zelda kidnapped' fanfiction might involve Link going on a heroic quest to rescue her. He could face various challenges like dangerous monsters and complex puzzles along the way. Maybe in the fanfiction, Zelda has been kidnapped by a powerful dark sorcerer who wants to use her for some evil plan, like draining her magic powers.
A 'Undertale kidnapped' fanfiction could also involve Frisk being kidnapped by a group of rogue monsters. These monsters might be angry at humans for sealing them underground and plan to use Frisk as a bargaining chip to negotiate their freedom to the surface. This would create a tense situation as the other friendly monsters would have to decide whether to side with the rogues or help Frisk escape.
There could be a fanfiction where Naruto is kidnapped during a mission. In this case, the story could explore how his ninja skills and his strong will help him survive while captive. It might also show the internal struggle of the kidnappers, some of whom may start to question their actions after getting to know Naruto better.
One interesting Kakashi x Naruto fanfiction could be where Kakashi takes Naruto on a special training mission outside of Konoha. In this story, Kakashi could teach Naruto some unique jutsu that he doesn't learn in the original series. This would not only strengthen their bond but also make Naruto a more powerful ninja.
One interesting 'Kakashi Kiss Naruto' fanfiction could be where Kakashi shows his deep affection for Naruto in a moment of extreme danger. He might kiss Naruto to transfer some of his chakra in a very unique and unexpected way, which is different from the normal chakra transfer methods in the Naruto universe.
A possible fanfiction could involve Kakashi being a member of a secret order in 'Game of Thrones' that protects the realm from threats that are not just political but also magical. He teams up with some of the more honorable characters in the series, like Jon Snow perhaps, and they go on adventures to fight off dark forces that are starting to rise in the land.
One interesting possessive Kakashi and Sakura fanfiction could be one where Kakashi is overly protective of Sakura during a difficult mission. He might use his skills and experience to keep her out of harm's way in a very possessive manner, like not allowing her to take on certain risks even when she wants to prove herself.