Yes, there are quite a few. You can start by looking on fanfic platforms like Archive of Our Own. There, you'll find a variety of stories that explore different relationships between Hatsune Miku and Kaito Shion. Some might be romantic, while others could be more of a platonic adventure. It really depends on what kind of story you're into.
Friendship is a very common theme. They are often depicted as good friends who support each other through various situations. Another theme is musical collaboration, since they are both Vocaloids associated with music.
Common themes include the exploration of their emotions. In fanfics, they might be trying to understand human - like emotions like love, jealousy, or friendship. Another common aspect is the idea of them being in a different world or time period. For example, some fanfics place them in a steampunk world where they use their musical talents in a whole new way. There's also the theme of protecting each other, as they are often depicted as having a special bond that makes them want to safeguard one another from harm.
I really like the interactions where Kaito Kid teases Conan. It's so much fun to see how Conan gets all flustered but still tries to be in control. For example, when Kaito Kid leaves behind little clues just to mess with Conan's detective skills. Another great interaction is when they actually have to rely on each other in a dangerous situation, like when they are trapped in an old building together.
A lot of Kaito Kid x Reader fanfics also play with the idea of identity. Kaito Kid has his secret identity as Kaito Kuroba, and sometimes the reader character might be in the dark about it or be the one to discover it. Adventure is another theme. The two characters might go on exciting adventures together, whether it's chasing after a valuable jewel or escaping from some pursuers. And there's always that element of Kaito Kid's charm and charisma that shines through in these stories, which is sort of like a sub - theme on its own.
One popular Vocaloid Kaito x Len fanfic is 'The Melodic Bond'. It beautifully portrays their relationship in a fantasy world where they collaborate on a magical musical journey. Another great one is 'Frozen Melodies' which delves into their emotional connection through a series of challenges they face together.
To develop the female Kaito, focus on her relationships. She could have a mentor - like relationship with an older female thief who teaches her the ropes. In terms of her skills, she might be more attuned to using technology in her heists compared to the male Kaito. Also, explore her motives. Is it for the thrill, for justice, or something else? Her emotional journey as she becomes more and more like a great thief is also important to develop.
In such fanfiction, Shinichi is often depicted as still having his sharp detective mind. He's intelligent, observant, and tenacious in solving problems. Kaito, on the other hand, is shown as his flamboyant self, with his amazing skills in magic and disguise. He's also quite charming. Both of them might have a bit of a competitive streak towards each other, which adds to the tension and interest in the story.
In luchia and kaito lemon fanfiction, Luchia could be characterized as a complex character. She might be a mermaid with a kind heart but also with insecurities due to her different world. Kaito might be depicted as a bit of an enigma, with his own secrets. Sometimes, in these fanfictions, their relationship is intensified, with more emotional and physical closeness. But we have to be careful as lemon fanfictions may not always stay true to the original characters' personalities. They might exaggerate certain traits for the sake of the more adult - themed storylines. It's important to look for fanfictions that respect the core of the characters while also exploring new aspects of their relationship.
Writers often start with the established personalities of Miku and Kaito. For Miku, her energetic and creative nature is usually emphasized. They might put her in situations where she has to use her creativity to solve problems. For Kaito, his cool and sometimes aloof exterior can be explored. Writers could make him open up more as the story progresses. They also might give them new skills or abilities related to music to make the story more interesting.