One common theme is rivalry. In the original source material, they might have a bit of a competitive relationship, and this often gets explored in fanfics. They might compete for the attention of a certain character or for a position in some group.
One common theme could be the exploration of the relationship between Yuki and Kyo in a new and unique context. Since mpreg adds an unexpected element, it might focus on how they deal with the pregnancy, both emotionally and practically.
One common theme could be the exploration of their relationship dynamics. Since it's yaoi, there might be a focus on the romantic and emotional connection between Kyo and Yuki.
One common theme is the idea of overcoming their rivalry. In many fanfics, they start off as enemies but gradually learn to respect and even care for each other. Another theme is self - discovery. Through their relationship, they often discover new things about themselves. For example, Kyo might learn to control his temper better and Yuki might become more open about his emotions.
I'm not sure specifically as I haven't read this particular fanfic. But generally, it might involve the relationship between Yuki and Kyo, perhaps exploring their interactions, emotions, and development in a fictional scenario.
Often, self - discovery within their relationship is also a theme. As they explore their feelings for each other on a deeper level in the fanfiction, they may also discover new aspects of themselves. This can be shown through their interactions, both in terms of dialogue and physical contact, which are often emphasized in 'lemon' fanfiction to create a more engaging and emotional story.
One good 'yuki x kyo fanfic' could be 'The Unlikely Bond'. It focuses on their relationship development in a really interesting way, exploring how they overcome their initial differences.
Another theme is the power of friendship turning into love. They start off as comrades or friends perhaps, and then the story shows how their relationship deepens into something more romantic. For example, in some fanfics, they go through adventures together which bring them closer and closer until they realize their true feelings for each other.
A common theme is friendship. Their relationship often starts as a friendship and then develops into something more meaningful. Another theme is adventure, as they usually embark on some sort of journey together.
A common theme is probably the discovery of love. Since they are two characters, the journey of them realizing they are in love with each other is often explored.
Another common theme is self - discovery. As they interact in the fanfics, both characters might learn more about themselves. For example, yuki could discover his inner strength with hatsuharu's support, and hatsuharu might learn more about his calm side through yuki. Fanfics use their relationship as a vehicle for these self - exploration journeys.