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.
There might also be other supporting characters from their respective universes. For example, from Gumball's world, Darwin could be involved. He's Gumball's best friend and fish - brother, and his presence could add more humor and friendship elements to the fanfic. And in Carmen's world, some of her allies or foes might make an appearance, which would bring in more action and drama.
The main characters are Carrie and Gumball. Carrie is a ghost girl with special powers and a unique personality. Gumball is a blue cat - like character who is always getting into all kinds of crazy situations.
Since I don't know the exact 'Gumball Love Story', I assume the main characters are probably the two gumballs in love. One could be a colorful and outgoing gumball, and the other might be a more shy and reserved gumball.
Gumball and Penny are the main characters in gumball and penny fanfic. Gumball is known for his zany antics and his ability to get into all sorts of trouble. Penny, on the other hand, is a bit more reserved but has her own charm. In the fanfic, their relationship is central. It could be a story of their first meeting, or how they deal with growing up and the changes that come with it. Maybe there are stories about how they support each other through difficult times at school or with their families.
I think focusing on the Wattersons family as a whole can be really interesting in a Gumball fanfic. You can show their family dynamics, like how Richard's laziness affects the household, or how Nicole's strictness is both a help and a hindrance. Then there are the friends like Carrie, the ghost girl. Her spooky nature and her friendship with Gumball and the others can add a unique element to the story. And Tobias, with his one - sided crush on Penny, can also bring in some elements of unrequited love and jealousy into the fanfic.
The main characters are Gumball, that blue cat - like creature with a big imagination, and Chichi. Chichi might bring a different kind of dynamic to the story. Maybe she's more level - headed compared to Gumball, which creates a great contrast in their interactions.
Darwin is a great character to pair with them. He's Gumball's best friend and also part of the family, so he can add a lot of fun and interesting dynamics to the story. Penny could also be a good addition. Her relationship with Gumball is unique, and in fanfiction, she can interact with Anais in new ways, like helping Anais with girl - related things. Richard, their father, can also be paired with them. His goofy nature can create some hilarious situations when combined with Gumball and Anais's adventures.
In some fanfictions, there could also be other characters from their respective universes that play important roles. For example, Gumball's family members might make an appearance and interact with Marshall, which could add more depth to the story and show different aspects of Gumball's life.
Obviously, Gumball and Chichi are the main characters. Gumball, with his zany and adventurous nature, and Chichi with her own unique charm and personality.