One common theme is family bonds. Since they are brothers in the original context, some fanfictions might explore the relationship in a different way, like a deeper emotional connection that could be misconstrued as something more romantic. Another theme could be protection, with Seto being very protective of Mokuba.
Another theme is the contrast between their two worlds. Seto's world of priesthood with its rules and Atem's more otherworldly nature. This contrast creates interesting dynamics and conflicts that drive the plot. In some fanfictions, they have to overcome these differences to be together.
One popular priest Seto x Atem fanfiction is 'The Bond Beyond Time'. It beautifully explores their relationship in a unique and captivating way. The story delves into their emotional connection and the challenges they face together.
Fanfiction.net is also a good place to look. However, the tagging system might be a bit different. Make sure to look for relevant categories and tags related to Yu - Gi - Oh! (assuming that's where these characters are from) and the specific relationship. Some authors might also post links to their works on social media platforms like Tumblr, so that could be another source.
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.
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.
I don't know what the fourth side story of the Soul Suppressing Priest refers to. If you can provide more information, I will try my best to answer your questions.
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.