Perhaps it's a story of her growth from an ordinary girl to a super girl in training. She starts out clumsy and unsure but gradually becomes more confident. Along the way, she makes friends with other superhumans -in - training, and they all support each other through the tough training sessions and battles against small - time villains.
The plot might involve her training under a strict mentor. She could be learning combat skills, how to use her powers for good, and also about the moral responsibilities that come with being a super girl. For example, she might have to decide between saving a group of people in a burning building or stopping a villain from stealing a valuable artifact at the same time.
Obviously, the super girl in training would be the main character. There might also be a wise old trainer or mentor who guides her on her journey.
Well, it could be about Gaara being a girl and having to face different challenges in the ninja world. Maybe she has to deal with different expectations from her family and the village compared to if she were male.
Well, it could be about a girl who has special powers and she uses them to save her town from an evil force. Maybe she discovers her powers gradually throughout the story.
It could be about a girl who finds herself in a strange situation where she is coiled by a snake. Maybe the snake has some magical powers and is protecting her from an unseen danger.
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.
The plot could involve Gaara trying to hide her gender while still being a powerful shinobi. Maybe she has to constantly worry about being discovered during battles or in interactions with other ninja. For instance, she might have to come up with excuses for not sharing certain spaces with male ninja.
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.
One possible plot could be that the girl is lost in a mythical realm where Cerberus guards. At first, she is scared of Cerberus, but gradually, through some kind of magic or special connection, Cerberus becomes friendly towards her and gives her a lick as a sign of acceptance.
Well, perhaps in the fanfic, a magic spell gone wrong turns Harry into a girl. He then discovers that being a girl in the wizarding world gives him a whole new perspective. He could start noticing things he never did before, like the way female wizards are treated in certain classes or by certain teachers. His relationships with other characters also change. For example, his relationship with Ginny could become more of a sisterly bond at first as he adjusts to his new form.
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.