Their fused form might have Goku's spiky hair, but with some of Goku Black's purple - tinted highlights. The body would be muscular like Goku's, but with a more menacing stance similar to Goku Black. The clothing could be a combination of Goku's orange gi and Goku Black's black under - shirt, maybe with some red accents added in for an extra pop of color.
Goku's ultimate form in the manga is Ultra Instinct. This state grants him enhanced combat abilities and reflexes. It's a breakthrough that showcases his potential and is a key factor in his toughest battles.
Goku's final form in the manga is Ultra Instinct. It's a state where his body and mind work in perfect harmony, granting him near-unbeatable abilities and reflexes.
Zamasu is often paired with Goku Black. Since they are closely related in the original story, fanfiction writers like to explore their relationship further. It could be about their shared goals or how they interact on a more personal level.
One interesting fanfiction could be about Goku and Black Goku teaming up against an even greater threat from another universe. In this story, they might initially be at odds but gradually learn to work together, using their unique abilities to save the multiverse.
In fanfiction about Goku and Goku Black, a common concept is the alteration of their power levels. Writers may give Goku new forms or boost Goku Black's abilities in unexpected ways. There can be stories centered around Goku Black's adaptation to the main timeline's culture and society. For example, he might have to deal with the everyday life in addition to his evil plans. And there are fanfictions that focus on the psychological impact of their battles on each other, like how Goku might be affected by constantly facing an evil version of himself.
A Goku and Goku Black fusion in fanfiction could be really exciting. The fusion would inherit Goku's love for fighting and getting stronger, but also Goku Black's ambition. Their combined ki could be a new type of energy that no one has ever seen before. This new fused form might also have new transformations or abilities. For example, it could combine Goku's Super Saiyan forms with Goku Black's Rose form in unexpected ways. It could change the power balance in the Dragon Ball world and open up all sorts of new storylines, like teaming up with other characters to take on new threats or even having internal struggles between the two personalities within the fusion.
It could be insanely powerful. Goku already has incredible power levels, and Goku Black is no slouch either. When they fuse, it's like combining two nuclear reactors. Their power could be so great that they could effortlessly destroy planets just by flexing their newfound power. They might be able to reach Super Saiyan forms that are far beyond what we've seen in the official series, with power levels that are basically off the scale.