You could try looking on Archive of Our Own (AO3). There are often many well - written Vocaloid fanfics there. Just search for 'Kaito x Gakupo' and you'll likely find some interesting ones.
Another theme can be adventure. They might embark on a journey to discover new sounds or to perform in far - off places. This gives the opportunity for the writers to create exciting scenarios and develop their characters further outside of the normal Vocaloid world.
The writing style also matters a great deal. If the author has a way with words, it can really bring the story to life. Vivid descriptions of the settings, whether it's a digital world or a more fantastical place, can enhance the overall reading experience of a Kaito x Gakupo fanfic.
Sure. One popular fanfiction might be 'The Adventure of Gakupo and Kaito' which has an interesting plot where they go on a musical journey together. It's full of great character interactions.
Romance can also be a theme, although it might be more of a subtext in some stories. It could be a slow - burn kind of relationship where they gradually realize their feelings for each other. And then there are stories that focus on their musical collaborations, like how they create amazing music together and what that process is like.
Romance is also quite popular. Writers like to explore the relationship between them in a romantic light, with cute moments and sometimes even some drama. For example, a story might be about them falling in love but facing some obstacles from the Vocaloid world's rules or other characters. And often there are themes of music - making together, as they are both Vocaloids associated with music. They might collaborate on a new song in the fanfiction, which also helps to develop their relationship, whether it's a friendly or romantic one.
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.
Another option is to check out some dedicated Vocaloid fan forums. Fans might share their own fanfictions or recommend good ones they've read. For example, the Vocaloid Otaku forum could be a great place to start exploring.
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.
Some dedicated Vocaloid fan communities or forums might also have fanfiction sections or threads where fans share their own works or recommend good ones. For example, the Vocaloid amino community could potentially have some great Len Kagamine x Kaito fanfictions shared by passionate fans.