If Sasuke becomes a girl, her appearance would transform in multiple ways. Physically, she'd probably have a smaller frame and less muscular build. Her hair could grow out to be really long and silky, which she might tie up with ribbons or hairpins. Her eyes could be made to look bigger and more alluring. Her skin might be smoother and have a bit of a glow. And she would start wearing more feminine accessories like earrings or a necklace. Her ninja outfits would also be redesigned to be more like a kunoichi's, with a shorter skirt perhaps and a more decorative top, while still maintaining some elements of her original style for the sake of recognition.
Next, consider how Link will react to becoming a girl. Will he be confused, angry, or curious? His emotions and internal struggle can be a big part of the fanfic. You can also think about how the other characters in the Zelda universe will react to his new form. Some might be accepting, while others could be more hostile or confused.
In the fanfic, Link could be magically changed into a girl due to a wish made by an innocent character. Link then has to find a way to reverse the transformation while still dealing with the challenges of the world. He might face discrimination or different expectations from others in his new form, which could add depth to the story.
Her character development would likely be different as a girl because she would face different challenges. For example, she might have to deal with the objectification that female ninjas sometimes face. This could make her more aware of gender inequality and she could become an advocate for female rights in the ninja world.
One possible aspect to consider in this fanfic could be the implications on Penny's relationships. Since she becomes a real girl, her interactions with Ruby and the others might change. For example, she could experience more complex emotions and form deeper bonds. Also, the way she views herself and her purpose in the RWBY world would likely shift. She might start to question her place among the humans and Huntsmen more deeply.
In a 'sonic becomes a girl fanfic', the story could start with some kind of magical or scientific accident that turns Sonic into a girl. She then has to navigate her world with a new body. She may discover new abilities or limitations. Perhaps she teams up with female characters in the Sonic universe more often now and they form a strong girl - power group to take on the bad guys. There could also be a focus on how Sonic adjusts to her new appearance and how it affects her relationships with characters like Knuckles, who may have a different dynamic with her now.
In a 'sans becomes a girl fanfic', perhaps Sans - now a girl - decides to use this new form to her advantage. She could try to infiltrate a group that was previously only male - dominated in the Underground. This would lead to a whole series of adventures as she tries to keep her true identity a secret while achieving her goals.
Well, it could be about Ash waking up one day as a girl and having to deal with all the changes in his, now her, life. Maybe she has to adjust to new social dynamics, different reactions from friends and rivals, and also how to handle Pokémon battles in a different body.
Well, it could be about Ben 10 being transformed into a girl and then having to deal with the differences in how society treats him/her. Maybe he/she has to face new challenges in using the Omnitrix while being a girl.
Obviously, Gohan as a girl would be the main character. His family members like Goku, Chi - Chi, and Goten would likely be in the story. They would have different reactions and interactions with Gohan in his new form.