Yes, there are many. You can start by looking on popular fanfic websites like Archive of Our Own. Some might focus on their relationship development from their different personalities and how they support each other in the story's universe.
A common theme could be identity exploration. Since the character is a female version of Shiba Tatsuya, the story might explore how this change in gender affects her place in the story's world. Another theme could be relationships, such as how she interacts with other characters in a different way compared to the male Tatsuya.
Well, in the original source, Tatsuya has some really cool powers. Fanfic writers see these and think, 'What if we took it to the extreme?' His overpowered portrayal in fanfiction is also because it allows for different types of stories. He can be the hero who saves the day with ease, or a more complex character who has to deal with the consequences of having so much power. It gives writers a chance to explore different themes like power and responsibility, and also just make really action - packed stories. For example, if Tatsuya can easily defeat any enemy, how does that affect the world around him? Writers can explore that in fanfiction.
Power dynamics can also be a theme. In some fanfictions, female Tatsuya Shiba might face different power structures in the magic world, and the story could revolve around how he overcomes or navigates these. For instance, there could be a story where he has to prove himself against female magic users who initially underestimate him.
The popularity might be due to the existing popularity of the Tatsuya and Mayumi characters. Fans love to explore different relationships and scenarios for their favorite characters, and fanfic allows them to do that.
One common theme is power exploration. Since Tatsuya has unique powers, fanfics often explore how those powers interact with the elements of other crossovers. For example, if he crosses into a world of superheroes, how his magic compares to superpowers.
Tatsuya and Miyuki are the key figures. Tatsuya might be portrayed as a very protective and resourceful person, especially now that Miyuki is pregnant. Miyuki could be shown as a loving and perhaps a bit nervous expectant mother. Their relationship dynamics and how they support each other during this time would be important aspects of the fanfiction.
The plot might involve them preparing for the baby's arrival. This could include things like setting up a nursery. Tatsuya, with his logical mind, might be in charge of making sure they have all the necessary supplies and security measures in place. Miyuki, on the other hand, could be more focused on the emotional aspect, like choosing the right baby clothes and imagining their future family life.
One common theme is self - discovery. The OC often discovers new things about themselves while being engaged to Tatsuya. For example, they might find new strengths or weaknesses. Another theme is love and sacrifice. Tatsuya and the OC usually have to make sacrifices for their relationship.
Well, finding good 'tatsuya and mayumi lemon fanfiction' can be a bit tricky. It depends on your personal taste. Some people might like ones that focus more on their relationship development, while others might prefer action - packed stories with them in it. You may need to read a few to figure out what suits you best. And always be cautious about the content quality and legality.