Gumball is sure to be one of the main characters, as it's in his name. His family members like Darwin and Anais are also very likely to be main characters.
One plot idea could be that Gumball loses his braces and has to go on a wild adventure to find them before his next orthodontist appointment. Maybe they got accidentally mixed up with Darwin's fishbowl accessories and are now at the bottom of the ocean.
It could be that the lesson is to not judge people based on their appearance or background. There might also be a message about the value of hard work and determination.
Since it's a fanfic, it may also bring in elements that the fans have always wanted to see. It might give Gumball some superpowers or put him in situations where he has to make really tough moral choices. The new gumball fanfic could be a great opportunity to see the world of Gumball from a different perspective, with new settings, new conflicts, and new ways for the characters to interact.
Maybe it's one of the school bullies who got hold of a magic book and decided to play a prank on Gumball by casting a love spell. They thought it would be funny to see him act all lovey - dovey, not realizing the chaos it would actually cause.
A more dramatic fanfiction could involve Marshall getting into some trouble with a group of bullies. Gumball, being the loyal friend, comes to his rescue. But in the process, they both learn some valuable lessons about standing up for themselves and the importance of friendship.
An interesting character interaction could be between Gumball and the school bully. The bully could make fun of Gumball's braces, but Gumball uses his quick wit and the braces as a sort of weapon. For example, he could shine the braces in the bully's eyes to temporarily blind him and make his escape. This would show Gumball's resourcefulness and also how the braces can be an unexpected asset.
Being slapped was a kind of physical injury, but it was also a kind of mental insult. When faced with a slap, people had different reactions. Some people chose to fight back, some chose to admit defeat, covered their faces, and walked away. There were also some who calmly analyzed the situation, accepted the lesson, or called the police. In some cases, slapping could also be seen as a form of punishment and discipline, such as in family education. However, slapping lessons could also lead to serious consequences. For example, after a student in Guizhou was slapped 11 times by a teacher, it caused dissatisfaction and controversy among parents. In short, slapping was a complicated action, and the consequences and handling methods varied according to the situation.
One great Gumball and Carrie fanfiction could be a story where they go on an adventure in a magical forest. Maybe they discover a hidden world full of strange creatures and have to work together to find their way back home. This kind of story would explore their friendship in a new and exciting setting.