One plot idea could be that Kaito Kid steals a precious jewel that has some hidden secret related to Shinichi's past case. Conan, while trying to solve the mystery of the jewel, has to team up with Kaito Kid who has his own reasons for stealing it. Another idea is that Shinichi, in his Conan form, is invited to a magic show by Kaito Kid where Kaito Kid uses the show to set up a mystery that only Shinichi can solve. And a third idea could be that a new villain emerges who targets all three of them, forcing Kaito Kid, Shinichi (as Conan), and the Detective Conan gang to work together to defeat the villain.
Well, a plot could involve Kaito Kid planning a heist at a place where Shinichi (as Conan) is investigating a different case. Their paths cross and they initially suspect each other. But as the story unfolds, they realize that there is a mastermind behind both situations. For example, an organization that wants to use Kaito Kid's skills and Shinichi's intelligence for their evil plans. In another scenario, Shinichi discovers that Kaito Kid has some information about the Black Organization that he is after. So, he has to find a way to get that information from Kaito Kid without revealing his true identity. This could lead to a series of cat - and - mouse games between them.
A possible plot in a fan fiction could be that Kaito Kid creates a grand illusion that causes chaos in the city. Conan, suspecting Kaito Kid's involvement, starts to investigate. Meanwhile, Shinichi in his own body (maybe due to a temporary antidote) also gets involved. They find out that Kaito Kid was actually trying to expose a corrupt politician. But in the process, they all get framed for the chaos. So, they have to work together to clear their names and also bring the real bad guys to justice. Along the way, there could be some interesting interactions between the three characters, like Kaito Kid teasing Conan about his small stature while Conan tries to outwit Kaito Kid with his detective skills, and Shinichi being the cool and collected one trying to solve the overall mystery.
A great plot might be that there's a mystery surrounding a rare and valuable magical artifact. Kaito is interested in it for its magical significance, while Shinichi is on the case because it's related to a theft. They initially suspect each other but then realize they need to work together. They discover that a shadowy figure is using the artifact's legend to cover up a more sinister plot.
One way to develop their relationship is through shared challenges. Suppose there is a new criminal in town who is a master of disguise and trickery, much like Kaito Kid but with evil intentions. Conan, Shinichi, and Kaito Kid all get involved in trying to catch this criminal. During the process, Kaito Kid can use his knowledge of magic and illusions to help Conan and Shinichi understand how the criminal operates. Shinichi can use his detective skills to analyze the criminal's motives and patterns. And Conan, with his unique perspective as a child, can notice details that the others might miss. This shared experience can bring them closer together, and they can start to see each other as allies rather than just adversaries. They might even start to exchange tips and tricks. Kaito Kid could teach Conan some simple magic tricks that can be useful in detective work, and Shinichi could share some of his deductive reasoning methods with Kaito Kid.
Rivalry is a very common theme. Kaito Kid and Shinichi are both highly intelligent characters, so their battles of wits are often central to the stories. For example, in many fics, Kaito Kid will plan a heist and Shinichi will try to stop him, creating a tense and exciting dynamic.
One great plot idea could be a team - up. Kaito Kid gets framed for a crime he didn't commit, and Conan has to help him clear his name while also trying to catch him in his thieving acts. Another could be a time - travel plot where they both end up in the past and have to work together to get back to their own time. Maybe they discover a common enemy from the past that is causing problems in the present as well.
One great piece of fanfiction could be 'The Heist and the Detective's Dilemma'. In this fic, Kaito Kid's elaborate heists start to involve Shinichi in unexpected ways, leading to a thrilling cat - and - mouse chase filled with mystery and some great character interactions.
In a fanfiction like this, a great plot could be that Shinichi and Kaito are in a relationship and Shinichi suddenly finds out he's pregnant. Kaito is initially shocked but then becomes super supportive. They could face challenges like how Shinichi's detective work might be affected. Also, they might have to deal with society's reactions as male pregnancy is not the norm. They could go on a journey to find a way to ensure Shinichi's and the baby's safety while also trying to figure out how this pregnancy came about in the first place, perhaps involving some villain's evil plan.
One idea could be to write a fan fiction where Conan has to solve a mystery in an ancient, haunted castle. The castle could have secret passages and hidden rooms filled with clues that lead to a long - lost treasure. Another idea is to create a story where Conan teams up with a new character who has a unique skill, like being able to communicate with animals, which helps them solve the case in a different way. You could also write a fan fiction that takes place in a different time period, like the future, and Conan has to adapt his detective skills to new technologies.
The rivalry between them. Conan is a detective and Kaito Kid is a thief. Their constant cat - and - mouse game makes for exciting stories. Each is trying to outwit the other.
Another idea is that they are at a masquerade ball. Shinichi is disguised as someone else, but Ran still senses his presence. They dance together and as the music reaches a crescendo, Shinichi reveals himself and kisses Ran. This would add an element of mystery and glamour to the story, as they are surrounded by other masked guests who are oblivious to their true identities.
In Detective Conan, Shinichi and Kaito rarely appeared at the same time, but there were some chapters where they appeared together as the main characters. For example, in Detective Conan: The Mystery of Fei Yingli, Shinichi and Kaito solved a case together as the main characters. Also, in Detective Conan: Kogoro's Reasoning, Kaito also participated in solving the case. Although Shinichi and Kaito rarely appeared together, they were both excellent detectives who worked together to solve cases and brought many exciting plots to the audience.