The theme of identity is also quite common. Ron has to figure out who he is now as a girl. Is he still the same person? How does his gender change affect his relationships? Additionally, there might be a theme of acceptance, both from himself and from those around him.
There might be a 'ron turns into a girl fanfic' where it's a part of a magical experiment gone wrong. Ron then has to deal with the reactions of his family. Hermione could be really helpful in guiding him through this strange new situation, and he might end up learning a lot about the female perspective in the wizarding world.
Well, one possible plot could be that Ron, as a girl, has to navigate the different social dynamics at Hogwarts. She might struggle with how the boys now treat her differently, and the girls might be either overly friendly or jealous. Maybe she would use her new form to get closer to Hermione in a different way, like understanding her on a more 'female - to - female' level. Also, she could have a whole new perspective on her own family, especially how her mother treats her now as a daughter in a different sense.
Another possibility is Snape. Snape might be suspicious of Ron's transformation and think it's some sort of dark magic at play. He could constantly be on Ron's case, trying to figure out what happened and making her life difficult in potions class and around the school in general. He might also suspect that Ron is up to something that could disrupt the order at Hogwarts.
First, you need to establish the reason for the transformation. It could be a magical spell gone wrong, or some kind of strange dragon - related phenomenon. Then, focus on how Hiccup adjusts to her new body. She'll have to deal with different physical abilities and limitations. For example, she might be physically not as strong as before, but more agile in some ways.
A fanfic could explore how Hiccup's transformation into a girl affects his friendships. Astrid might react in a complex way. At first, she could be jealous or confused, but then they could form a stronger bond. Also, Hiccup's father, Stoick, might have a hard time adjusting to his son becoming a daughter, which could add a lot of emotional depth to the story.
One possible scenario in this fanfic could be that Tony Stark, through some sort of magic or scientific experiment gone wrong, turns into a girl. This could lead to a whole new set of adventures and character developments. For example, his relationships with other characters like Steve Rogers (Stony) would be completely different. He might have to face new challenges in a different physical form, such as how society and his friends would accept him. Also, his own self - perception would change, and he'd have to re - evaluate his identity.
Well, in a 'freed turns into a girl' fanfic, the plot might start with an experiment gone wrong. Freed was perhaps trying to enhance his magic power and something in the experiment caused his physical form to change to that of a girl. He would have to deal with the reactions of his guildmates. Some might tease him, while others would be more understanding. And he would also face challenges like how to adapt to the new body's physical limitations while still being able to participate in guild activities.
The fanfic might also explore how Issei's powers are affected by the transformation. In the original Highschool DxD, Issei has his own set of abilities as a male. But as a girl, he could either have new powers related to femininity in that universe or his existing powers could be modified. This could lead to new battles and challenges where he has to learn to use his powers in a different way.
Well, one possible plot could be that Deku accidentally drinks a strange potion created by a villain. This potion has the side - effect of changing his gender to female. At first, he's shocked and confused. But then, he realizes that he can use this new form to his advantage in hero work. For example, he might be able to infiltrate a female - only villain group more easily. He also has to deal with his friends' reactions, some are surprised while others are supportive and help him adjust to his new body while still being a hero.