It's also because their personalities are so different yet complementary. Sulley is big and strong while Mike is small and smart. Fanfiction writers can play with these characteristics in various ways. For example, they can create stories where Mike's ideas and Sulley's ability to execute them lead to amazing results. This contrast makes for interesting and engaging stories.
Another factor could be the world of Monsters Inc itself. It's a unique and imaginative setting. Fanfiction writers can expand on this world in their stories about Sulley and Mike. They can introduce new monsters, new areas in the factory, or new rules in the monster world that Sulley and Mike have to navigate, which is very appealing to fans.
One good example could be fanfictions that focus on their adventures outside of work. For instance, a story where they go on a trip to a new, uncharted part of the monster world. Another might be ones that explore their friendship during their childhoods, like how they first met at monster school.
Maybe in the fanfiction, Sulley discovers that Randall has a hidden side. Randall might be secretly trying to protect the monsters from a new threat in the human world that no one else is aware of. Sulley initially doubts Randall but as he sees the evidence, he decides to help Randall. They then team up and use their different skills - Sulley's big and strong nature and Randall's sneaky and intelligent ways - to overcome the threat and in the process, their relationship changes for the better.
It's also about the unique relationships that can be formed. Mike could be a friend, an enemy, or something in between to the animatronics. Different fanfictions explore these relationships in various ways, which is very appealing to readers.
The Monsters Inc sad story is touching because it shows the depth of the characters. Sulley's journey from being a regular scarer to realizing the harm they were doing was a long and emotional one. And when he finally made the choice to do the right thing, it was sad because it meant leaving behind a part of his old life. The story makes you think about how hard it can be to let go of the past and move towards a more ethical future.
One common theme could be the exploration of their unique relationship in a more romantic or intimate way. Since they have a strong friendship in the original, the fanfic might build on that to show a deeper emotional connection.
In a different take, Sulley and Randall could be partners in a secret experiment within Monsters Inc. They might be working on a new way to collect energy from kids without scaring them. As they work closely together, they discover that they have a lot in common when it comes to their love for the monster world and their hopes for its future. This shared passion could lead to a deeper bond between them, different from the adversarial relationship in the movie.
Friendship is a very common theme. Since the OC is a new character, often the story focuses on how they become friends with Sulley. For example, they might help each other out in tricky situations at Monster Inc.
I'm sorry, but I don't have specific sulley x mike yaoi fanfic to recommend directly. You could try searching on fanfic platforms like Archive of Our Own. They usually have a wide variety of fan - created works.
Sulley and Mike are definitely the most popular. Sulley is the big, furry blue monster who is the star scarer, and his relationship with Mike is really fun to explore in fanfiction. Boo is also very popular as she is the cute human girl who befriends the monsters.
Monsters Inc. is set in a world where monsters generate energy from children's screams. But as the story progresses, we discover that laughter can generate even more powerful energy, leading to a major shift in the monsters' way of doing things.