The plot could involve a new villain who targets both of them because of their relationship. This villain might be someone who wants to disrupt the harmony between Earth and the cosmos. Spider - Man and Captain Marvel have to work together to defeat this enemy while also dealing with the challenges of their new - found married life.
Perhaps they discover a new power that emerges when they are together as a married couple. This power could be crucial in saving the multiverse from a great threat. The fanfic could then be about their journey to understand and master this power, all while maintaining their relationship and dealing with the public eye as a married superhero couple.
One possibility in such a fanfic could be that they meet during a major inter - galactic crisis. Maybe they start off as allies, gradually realizing they have deep feelings for each other. Their different powers could combine in interesting ways to save the day, and this shared experience could be the start of their romantic journey towards marriage.
The plot might involve an interdimensional force that accidentally merges the worlds of Spider - Man and Captain Marvel in a way that forces them into a shared adventure. They could be in a situation where they have to protect a group of innocent people caught in this strange merge. Since they are from different hero backgrounds, they initially clash but then gradually learn to work together as they face greater threats.
One idea for a Captain Marvel and Spider - Man fanfic could be that they team up to fight a common enemy from another dimension. Maybe a powerful alien force is trying to invade Earth, and their combined powers are needed to stop it. Captain Marvel with her energy - based powers and flight, and Spider - Man with his agility and web - slinging skills would make an awesome duo.
Another scenario could be that there is a power struggle. Captain Marvel is seen as a very powerful hero, and Spider - Man might feel that she is overstepping in New York (his territory). So, he starts to oppose her actions, which escalates into a full - blown feud. This would involve some intense confrontations where both would have to use their powers to the fullest.
One possible fanfiction could involve Spider - Man and Captain Marvel teaming up during the Endgame battle. Maybe Spider - Man uses his agility to distract the enemy while Captain Marvel blasts them with her powerful energy. They could also have some fun banter, like Spider - Man making a joke about how Captain Marvel can fly and he has to swing around.
In a fanfiction like this, there could be a lot of challenges. Their different backgrounds - Peter Parker's normal life as a student and Carol Danvers' military - turned - superhero past - could create some interesting conflicts. But they could also learn from each other. Spider - Man could teach Captain Marvel about the little joys of a normal life, and she could show him how to be more confident in the big superhero world.
A possible plot could be that an ancient artifact has been stolen and it has the power to disrupt the balance between Earth and Asgard. Captain Marvel and Valkyrie are both called upon to retrieve it. They initially suspect each other of having ulterior motives but soon realize they are on the same side. They then embark on a journey filled with battles against various intergalactic pirates and magical creatures who also want the artifact for themselves.
A great fanfic might involve a scenario where Spider - Man gets transported to a different dimension where Captain Marvel is in trouble. He has to use his wits and skills to help her out. Their relationship could start as a bit of a rocky partnership but grow into a strong friendship as they face challenges together. In this fanfic, there could be some really cool action scenes with Spider - Man swinging around while Captain Marvel is flying and blasting enemies.
One plot idea could be that they meet in an alternate dimension where they are the only ones who can save that world. During their adventure, they fall in love and decide to get married. But when they return to their own world, they have to deal with the reactions of their friends and the public.
Another fanfiction concept could be a mentorship situation. Spider - Man looks up to Captain Marvel as a powerful and experienced hero. She could train him to better control his powers and also teach him how to handle the pressure of being a hero on a larger scale. This could involve some intense training sessions where Spider - Man has to push his limits, and Captain Marvel shares stories from her own experiences in the galaxy.