It's fairly common. Fans often look for more content related to their favorite shows. Since 'Attack on Titan' has a large and passionate fan base, there are a lot of fanfics available. 'Aot' fans might watch (read) these fanfics to explore different scenarios that the official story didn't cover. For example, they might want to see how a certain character would react in a different situation or what would happen if a major plot event had a different outcome.
They might be characters from a specific genre of story. For instance, if it's a romantic comedy, Sonny could be a bubbly girl and Chad a bit of a shy but charming guy. They could be neighbors or coworkers, and their relationship develops in a humorous and heartwarming way.
There could be various fanfictions. Maybe some that focus on alternative endings, like ones where certain characters survive who didn't in the original. For example, a fanfiction where Erwin survives and leads the Scouts in a different way.
Once upon a time, the reader was walking in the neighborhood when they stumbled upon Mr Kat. Mr Kat was up to his usual antics, plotting against Kid. The reader, being a kind - hearted soul, decided to intervene. They tried to reason with Mr Kat, explaining that Kid was just a kid having fun. Mr Kat scoffed at first, but as the reader continued to talk, he started to listen. In the end, Mr Kat and the reader formed an unlikely friendship, and Mr Kat decided to give Kid a break.
It could mean that a person who is a fan of 'Attack on Titan' (AOT) is reading or watching fan - created fictional works related to AOT. Maybe they are interested in seeing different interpretations or storylines that fans have come up with.
One way is to check on popular fanfiction websites. Look for ones with high ratings and a lot of reviews. For example, Archive of Our Own (AO3) has a large collection of AOT fanfictions. You can search for the most popular ones there.
Once upon a time, the Reader found themselves in the middle of the chaos between Kid and Mr. Kat. Kid was always up to his mischievous antics, much to Mr. Kat's annoyance. The Reader decided to try and mediate. They talked to Kid, explaining that Mr. Kat was just trying to keep things in order. Kid was hesitant at first but then started to listen. Mr. Kat, seeing the Reader's efforts, was also more open to Kid's youthful energy. In the end, they all found a way to coexist more peacefully.
One popular character to include could be Coop's sidekick or pet. It could add some comical relief to the story. Another might be a mentor - like figure who gives advice to Kid and Fem Kat during their adventures.