Goku's understanding of different universes and races could be deepened in fanfiction. Since Dragon Ball Super introduced the multiverse concept, fanfiction could explore how Goku interacts with and learns from beings from other universes, making him more worldly and less naive in some ways.
Claudia is not a character from the original Dragon Ball series. Goku is the main protagonist of Dragon Ball. He is a Saiyan sent to Earth as a baby. He is known for his powerful fighting abilities, his love for martial arts, and his kind heart. He has saved the Earth multiple times from various threats.
There's a fanfic called 'Goku's Hidden Power'. In this story, Goku discovers a new level of power within himself that even the Kais didn't know about. It delves deep into Goku's character, exploring how he copes with this newfound strength and the responsibility that comes with it. The action scenes are also very well - written.
In a fanfiction, Goku might be weakened due to a curse. He loses his Super Saiyan powers and has to start from scratch. This could lead to a great character - development arc. He might discover new ways to fight without relying on brute strength, like using his wits and strategic thinking more, and also learning new martial arts techniques from his human friends.
Perhaps a fanfiction where Vados senses a new threat approaching the universe. She enlists Goku to help her find a way to stop it. Along the way, they encounter strange new races and powers. Goku's simple but powerful approach to fighting combined with Vados' wisdom would make for an interesting dynamic as they search for a solution to this impending doom.
Well, one way is to look at different species in the Dragon Ball universe. For example, take the Saiyan and mix it with some other unique traits. Maybe combine Saiyan genes with the Namekian ability to regenerate. Writers could also consider environmental factors that might cause a mutation. What if Goku was exposed to some super-rare energy during a battle in a far - off planet? Another idea is to play with magic or ancient powers. If there's a long - forgotten spell that alters his genetic makeup in a strange way, that could lead to a really cool mutation.
In some fanfics, Goku SSJ's character development might focus on his relationship with his family. He could become more protective and understanding of his family's needs. For example, he might take more time to train Gohan and teach him important life lessons along with martial arts skills.
One of the interesting power - ups could be his Ultra Instinct form. In fanfiction, it might be further enhanced, like having different levels that are not shown in the original. For example, he could have an Ultra Instinct - Kaioken combination which would be extremely powerful.