One interesting Zamasu fanfic could be about his origin story in more detail. It might explore his early days in the Kaioshin realm, his training, and how his ideology started to form.
One common theme is the power dynamic. Since Gogeta is very powerful, female characters in the fanfiction might either be in awe of his power or strive to match it. For example, a female Saiyan could train hard to be as strong as Gogeta.
Another theme is the exploration of power. Since Gogeta is extremely powerful, in these fanfics, the female character might either be in awe of his power or strive to match it. For example, some fanfics show the female character training hard to reach Gogeta's level of strength.
One common theme is the exploration of their relationship, whether it's a friendship or something more complex. Another theme is the role of Bulma in Gogeta's more action - packed world. For example, in some fanfics, Bulma uses her intelligence to help Gogeta in battles. Also, the idea of how their two different personalities interact is often explored.
One idea could be a crossover with the Dragon Ball Super universe and the DC Comics universe. Zamasu could team up with Darkseid, believing they share a similar view of bringing 'order' to their respective realms. Another idea is a crossover with the Naruto universe, where Zamasu tries to impose his will on the ninja world, facing off against powerful shinobi like Naruto and Sasuke. Or perhaps a crossover with the Star Wars universe, with Zamasu as a Sith - like figure, trying to gain control over the Force.
The idea of an alternate universe is also very common. Since Zamasu is from a different franchise, fanfictions like to create a new world where both Naruto and Zamasu co - exist. This allows for new character relationships to be formed, new storylines to be developed, and for the writers to be really creative with the setting and the overall plot.
One common theme is the clash of ideologies. Naruto has his values of friendship and protecting the village, while Zamasu has his own extreme views. So, this often leads to interesting conflicts in the fanfics.
Redemption could also be a theme. Although Zamasu in the original was quite villainous, a female Zamasu in fanfic might be on a journey of self - discovery and redemption. She could start as a bad character but gradually change due to certain events or interactions in the story.