An OC who is a street - smart mouse with a network of informants all over the city could be interesting. This OC could come across a strange occurrence that they think Basil should know about, leading to a new adventure. They could provide Basil with valuable leads from their connections on the streets.
The OC could be from a different part of the mouse world with unique skills, like being able to communicate with certain insects that can help in solving crimes. For example, they could get information from a spy spider about a villain's lair location. The OC then teams up with the great mouse detective to use this new lead to solve a big case.
One idea could be Basil solving a mystery in a new, strange part of the mouse city, like an abandoned underground area filled with old secrets. Another could be Basil teaming up with a new, young mouse detective in training to solve a case that's baffling the entire mouse detective community. Or perhaps a story where Basil has to solve a mystery on a ship sailing to a far - off mouse - inhabited island.
One idea could be a crossover with Sherlock Holmes in the human world. The great mouse detective could team up with Holmes to solve a mystery that spans both the mouse and human realms. Maybe there's a villain causing chaos in both worlds and their combined skills are needed.
One idea could be an OC who is a detective trainee and teams up with Detective Pikachu to solve a mystery in a new part of the Pokemon world. Maybe they are investigating a series of disappearances of rare Pokemon. Another plot could involve an OC with a special ability to communicate with certain types of Pokemon that Pikachu can't, and together they use their combined skills to stop a villain who wants to use these Pokemon for evil.
A mystery - themed 'the oc fanfic' would also be great. Maybe there's a mystery surrounding the Cohen family's wealth or a long - lost relative that suddenly shows up with a hidden agenda. The characters would have to work together to solve the mystery, and in the process, their relationships would be tested and new alliances formed.
One idea could be exploring an OC's (Original Character) journey to become a leader within the 100's post - apocalyptic world. They could start as an outcast and through their unique skills, like advanced medical knowledge or exceptional hunting abilities, gain the respect of different factions.
A believable 'The Great Mouse Detective' OC should have flaws. Maybe they are too impulsive and often get into trouble because of it. Their appearance can also play a role. For instance, if they have a scar from a past encounter, it can add depth to their character. And don't forget to give them a goal or motivation, like seeking revenge for a wrong done to their family.
An OC could be a street artist in Ikebukuro who uses their art to tell the stories of the various gangs and groups in the area. This OC could interact with Celty as they both have an interest in the unique aspects of the city. They might start a project to document Celty's presence in a positive way, which could draw the attention of the Dollars and other factions.
One idea could be that your original character (OC) is from another planet similar to Krypton. They arrive on Earth and initially clash with Superman over different approaches to protecting the planet. But as they face a common powerful enemy, they learn to work together and combine their unique powers.
A cool plot could be an OC who has the ability to communicate with Titans in a different way than the normal Seeker. Instead of using the traditional methods, they can enter the Titans' minds and see their memories. This leads to the OC finding out about a hidden danger that threatens all of Huntik, and they have to convince the other Seekers to believe them and take action.