She might use her superpowers accidentally during a school sport event, like making the basketball she throws fly all the way across the field and into the neighboring town.
Well, she could meet a young villain - a student who has some sort of power - in the school. This student might be jealous of Captain Marvel's fame and power. They could start a mini - power struggle within the school grounds. Captain Marvel would have to use her wits and powers carefully to stop the situation from getting out of hand without causing too much damage to the school.
In the 'Captain Marvel goes to school fanfic', perhaps she has trouble fitting in at first. She's used to outer space battles, but now she has to deal with high school cliques. For example, the popular kids might be a bit intimidated by her and the nerds might be overly eager to be her friend because of her superpowers. She could also struggle with normal school subjects like math and history, having been out of touch with Earth's educational system for so long.
She could meet a very smart science teacher who is intrigued by her powers and wants to study them scientifically.
Well, it could be a really exciting scenario. Captain Marvel is extremely powerful, so if she 'raids' Peter's fanfic world, she might disrupt the story in a big way. Maybe she accidentally changes the plot or gets into a misunderstanding with Peter. For example, she could think Peter is involved in something dangerous when he's just dealing with normal Spider - Man stuff in the fanfic.
In a 'Captain Marvel Meet the Avengers' fanfic, there could be an epic showdown against a powerful villain. Captain Marvel's immense power combined with the Avengers' diverse skills would make for an amazing battle. For example, she could team up with Thor to take on an enemy that has the ability to control electricity. Their combined strength of her photon blasts and his lightning strikes would be a sight to behold.
There could also be a story where Captain Marvel has to prove herself to the Avengers. She might be seen as an outsider initially. So she has to show her worth through her actions. She could single - handedly take on a group of powerful villains to gain the Avengers' respect, and then they all work together towards a common goal.
Well, in a 'Percy Goes to School Fanfic', Percy might face some bully problems at school. Maybe there are some mean kids who pick on him because he's different.
In a fanfic where Captain Marvel is abused in a Young Justice context, it could lead to a very dark and complex storyline. Maybe it shows his struggle to maintain his heroic nature while dealing with such trauma. It could also explore how the other Young Justice characters react to this situation, whether they try to help him or are themselves in danger due to his abuser.
One possibility is that Ash would be a bit of a star at the Pokemon school. Since he has so much experience traveling and battling. He could inspire other students to be more adventurous with their Pokemon. Also, there could be some unique Pokemon species that are only studied at the school which Ash gets to interact with.
Captain Marvel could help decorate an entire city for Christmas. With her powers, she could easily place the star on the tallest Christmas tree or hang lights all over the town in no time. And along the way, she might inspire the people in the city to come together and celebrate the holiday spirit. She could also be involved in a story where she has to stop a Christmas - themed supervillain who is using the holiday to carry out some evil plan, like stealing all the presents in the city to make everyone sad on Christmas day.
Well, perhaps the other characters in the Young Justice universe might take advantage of Captain Marvel being asleep. They could play a prank on him or have a serious discussion about what to do with him while he's out. Maybe they'd try to figure out if he's in some kind of danger that caused him to fall asleep suddenly.
There could be an emotional side to it as well. His friends in Young Justice would be worried about him. They would visit him while he's sick, and there could be some really touching moments. Maybe Wonder Girl would try to cheer him up with stories of their past adventures, and these interactions could show the strong friendship within the team.