In such fanfiction, Yuuki might be depicted as more alluring and perhaps more assertive in her relationship with Zero. Zero, on the other hand, could be shown as more brooding and possessive. However, this is a very general view and can vary greatly depending on the author's interpretation.
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.
Kirito is more of a traditional swordsman in terms of his combat style. He often relies on his sword - fighting skills and his ability to quickly analyze his opponents. Yuuki, on the other hand, has a very unique and flashy fighting style. Her movements are more acrobatic.
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.
If Seto is watching Yugi for Yami, it could lead to a more complex relationship. Seto might start to see Yugi in a different light, perhaps not just as an opponent but as someone with a unique bond with Yami. This could lead to a grudging respect for Yugi.
The abuse from Gozaburo could lead Seto to have a more complex view of power. He may start to see power not just as a means to an end, but also as something that can be misused. This realization could make him more careful in his own pursuit of power and more empathetic towards those who are powerless, which is a significant shift in his character.
There could be. Fanfiction writers like to play with different character dynamics. In some fan communities, writers might take the idea of Yuuki being both Kaname's sister and lover and build an entire fictional story around it. But it might not be to everyone's taste.