There could be a fanfiction where baby Conan is taken care of by the members of the detective boys group. They try to figure out why he is so intelligent for a baby. In this story, they might have funny adventures while trying to protect Conan from potential threats that might be interested in his extraordinary intelligence.
One interesting detective conan baby fanfiction could be about Conan as a baby having some special powers that he unknowingly uses to solve mini - mysteries around him. For example, he might be able to communicate with animals in a way that gives him clues to find a lost item in the neighborhood.
One interesting fanfiction story could be about Conan and Haibara teaming up to solve a mystery that involves a new type of poison. They use their combined scientific knowledge and detective skills to track down the culprit. Haibara might use her knowledge of the black - organization's chemical experiments to figure out how the poison works, while Conan uses his sharp deductive reasoning to find the person behind it all.
Some Detective Conan fanfiction novels are about time - travel scenarios. Imagine Conan going back in time to prevent the initial incident that led to him being shrunk. It's a really cool concept. Also, there are fanfictions where the Black Organization has different motives and more complex hierarchies. This can add a whole new layer of mystery and intrigue to the story. Oh, and fanfictions that feature crossovers with other detective or mystery series can be really interesting too.
One idea could be creating an OC who is a master of disguise, like Conan, but with a unique backstory. Maybe they are from a different country and have their own reasons for getting involved in the detective work in Japan. Another idea is an OC that has a special gadget - something that hasn't been seen in the original series yet, like a device that can analyze poisons instantly. And a third idea could be an OC who is a childhood friend of Shinichi's that has some hidden talents related to solving mysteries that come to light after his transformation into Conan.
One idea could be a crossover with Sherlock Holmes. Conan could meet Holmes in London and they could solve a complex mystery together. Holmes' deductive skills and Conan's modern knowledge would make for an exciting combination.
Well, the love triangle involving Kazuha, Heiji and another character can be quite engaging. Kazuha has deep feelings for Heiji, but Heiji is often so focused on solving cases that he sometimes overlooks her feelings. This creates a lot of misunderstandings and tender moments between them as Kazuha tries to get Heiji to notice her more in the context of love rather than just as a friend in detective adventures.
Well, in some of the short stories, there are cases related to art theft. For example, a valuable painting goes missing during an exhibition. Conan notices small details like the behavior of the security guards, the layout of the gallery, and some peculiar marks on the wall near where the painting was displayed. By putting all these together, he's able to figure out who the thief is. It's really fascinating how he can solve such complex cases with just his observational skills and knowledge of crime.
One idea could be that Harry Potter travels to the world of Detective Conan. He could use his magic to help Conan solve some cases that seem impossible with just normal detective skills. For example, he might use a spell to reveal hidden clues or to track down a suspect who has magically disappeared.
Well, you could have an OC that is a childhood friend of Shinichi who has a photographic memory. This OC could recall small details from their past that end up being crucial in solving current cases. Or perhaps an OC who is an expert in a very specific field, like ancient languages, and Conan has to rely on this OC's knowledge when a case involves old inscriptions or manuscripts. Also, an OC who has a connection to the Black Organization, either as a former member trying to reform or someone unknowingly involved in their plans, could add a lot of drama to the fanfiction.
One interesting concept could be Conan traveling back in time to prevent the initial crime that led to his shrinking. He might be able to use his knowledge of the future to stop the Black Organization from ever getting to the point of drugging him. This would completely change the course of the story and perhaps even prevent the many tragedies that followed in the original plot.
One idea could be that Harry Potter and Conan end up in the same magical - mystery world. Harry uses his magic skills while Conan uses his detective skills to solve a case that involves dark wizards and a powerful, mysterious artifact. Another idea is a crossover where the characters from Hogwarts visit Conan's world, and they all have to work together to figure out a series of strange disappearances that seem to be related to a new type of magic or potion.