Osana Najimi might also be a popular character. She can be involved in the fanfiction as a friend or foe to Midori. If the story is set in the school environment typical of Yandere Dev's work, Osana could play a significant role in the power struggles or relationship dynamics. Additionally, Info - chan could be included. She has her own mysterious nature, and her interactions with Midori could be full of intrigue and mystery.
In some yami and seto fanfictions, Yami might be depicted as the more mysterious and powerful one. Seto, on the other hand, is often shown as the proud and wealthy character. Their interactions can range from intense rivalries to unexpected alliances or even romantic undertones. However, in lemon fanfictions, these characteristics can sometimes be exaggerated for the sake of the plot.
Friendship is a common theme. They often start as friends and then develop a deeper bond. Another theme is growth, both as individuals and in their relationship.
Without having read her works, it's hard to say exactly. But in general, an author's unique touch in science fiction can come from their world - building. Maybe Takase Midori creates really immersive and different future or alien worlds.
Maybe Seto is trying to understand Yugi better in order to outwit him in some future duel. He could be observing Yugi's mannerisms, strategies, and how he interacts with Yami, all to gain an edge.
Maybe Mokuba would be a crucial character. As Seto's brother, he would be deeply concerned about his brother's transformation. He could be the one staying by Seto's side the most, trying to comfort him and also helping the others figure out how to reverse the spell. Another character could be Kaiba's business rival who might see this as an opportunity to take over KaibaCorp, adding some conflict to the story.
Seto's usually cold and calculating personality might soften. He could start showing more vulnerability around Joey. For example, he might let Joey see him without his usual confident facade when they're alone. Joey, on the other hand, might become more responsible. His impulsive nature could be tempered as he realizes he has someone he really cares about in Seto.
I'm not very familiar with Takase Midori specifically in the science fiction genre. You could try searching for her works in specialized science fiction libraries or online bookstores.
Often, there are themes of power dynamics. Midori might find herself in a situation where she is either overpowered by a yandere character or has to find ways to gain power in the face of such an obsessive figure. It can also be about the corruption of innocence. If Midori is depicted as an innocent character, the fanfiction could show how the yandere influence slowly changes or taints her.