Maybe in the 'Steven becomes a girl fanfiction', Steven wakes up one day as a girl. He might start exploring new fashion styles and interests that are more typically associated with girls. He could also struggle with his own identity, trying to figure out if he's still the same person inside while looking so different on the outside.
Well, it could be about Steven having some sort of magical or scientific accident that turns him into a girl. Then he has to deal with the new body, different social expectations, and how his friends and family react to this big change.
Besides Steven, the main characters could include the villains he's faced in the past. Now that he's a girl, they might underestimate him or treat him differently. His father Greg could also play a big role. Greg might be a bit shocked at first but then would be super supportive, trying to understand what his 'new' child is going through. And there could be new characters introduced, like other girls in the town who become friends with Steven and help him adapt to the female world.
Perhaps the fanfiction could start with Steven having a strange dream about Pink Diamond. When he wakes up, he starts to notice small changes in himself, like his gem glowing pink more often or having strange new abilities. As he becomes more and more like Pink Diamond, he realizes that there is a connection between his mother and himself that he never fully understood. He then embarks on a journey to discover the truth about his transformation, along the way facing challenges from both the Homeworld and Earth - based gems who are either afraid of or intrigued by his new form.
Well, maybe Ben 10 gets transformed into a girl by some alien device malfunction. Then he has to deal with all the new experiences like how people treat him differently, and he might discover new powers related to his new form.
Well, it could be that Percy wakes up one day as a girl and has to navigate the world with a new perspective. Maybe she now has to deal with different social expectations and relationships. For example, her friendships might change as her friends react to her new form.
One possible plot could be that Yugi wakes up one day as a girl and has to deal with the shock and confusion. His friends might be initially startled but then accept him/her. He/She could then face new challenges in dueling as a girl, like opponents underestimating her.
A simple plot could be Baby Steven getting lost in the woods near the Crystal Gem base. He encounters some friendly forest creatures who help him find his way back. As he wanders, he discovers new magical elements in the forest that the Gems didn't even know about.
If Steven turns into a girl in fanfiction, it could change the way he interacts with the other characters. For example, his relationship with Connie might become more complex, as they could explore a different kind of friendship or even a romantic relationship. Also, the way the Crystal Gems protect him might change, as they may see him as more vulnerable in his new form.
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.