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.
One common theme could be the exploration of power dynamics. Since one character is submissive and the other is dominant, the story might delve into how they navigate this relationship in different situations. Another theme could be character growth, as the submissive character may learn to assert themselves in certain ways while still maintaining the relationship dynamic.
One common theme is the transformation of their rivalry. They start off as bitter rivals in the dueling world but then often find common ground. Another theme is mutual respect. As they get to know each other better through various plotlines, they begin to respect each other's skills and determination.
The main characters are Joey and Seto, of course. Joey is often depicted as a more impulsive and passionate character, while Seto is more calculating and reserved. In the context of mind control fanfiction, their personalities play a big role in how the story unfolds. Joey might be more vulnerable to the mind control in some stories because of his more emotional nature, while Seto would be the one trying to figure out what's going on and find a solution.
One common theme is rivalry - their long - standing competitive nature in the Duel Monsters realm. This often serves as a starting point for the relationship to develop.
You can try looking on fanfiction websites like Archive of Our Own (AO3). They have a vast collection of fanfictions across various fandoms. Just search for 'female Joey x Seto pregnancy' in their search bar, and it might show you relevant stories.
One possible plotline could be that the mind control is used as a way to make Joey and Seto understand each other better. For example, through the mind control, Seto might see Joey's insecurities and the real reasons behind his actions. Another could be that an external force uses mind control on Joey to make him do things against Seto, creating a lot of conflict and drama as Seto tries to figure out what's wrong with Joey and how to break the control.
A common theme could be the exploration of their relationship dynamic. Given their different personalities in the original Yu - Gi - Oh! series (assuming they are from there), fanfics might focus on how they overcome their differences. For example, Seto's cold and calculating nature vs Joey's more hot - headed and impulsive one.
Another theme is the power of love. Despite Joey's amnesia, the love between them (in the context of the fanfic) still shines through. It might be a bit of a struggle at first, but it always manages to prevail in the end.