I'm not entirely sure specifically what a 'beerus raps beerus fanfic' is about without more context. It could potentially be a fan - created story where the character Beerus is rapping. Maybe it involves Beerus expressing his thoughts, his powers, or his experiences in the form of rap within the context of a fan - made fictional narrative.
You could try looking on fan - fiction websites like Archive of Our Own or FanFiction.net. They usually have a wide variety of fan - created works, and there's a good chance you might find a 'beerus raps beerus fanfic' there.
I think it depends on various factors. Goku's determination and growth are remarkable, but Beerus has an overwhelming level of power and authority that might be difficult to overcome.
A different take on a Naruto - Beerus fanfiction could be a story where Beerus decides to train Naruto. Beerus is an extremely powerful being, and his training methods would be very different from what Naruto is used to in the Hidden Leaf. This training could unlock new levels of power for Naruto, and also lead to some humorous moments as Naruto tries to adapt to Beerus' strange ways.
Sasuke can also be quite popular in Naruto - Beerus fanfiction. His rivalry with Naruto and his own quest for power can be interestingly intertwined with the arrival of Beerus. In some fanfictions, Sasuke might see Beerus as a new challenge or an opportunity to gain more power.
One common theme is power dynamics. Since Beerus is a powerful deity and Shin is also a significant figure, their relationship in terms of who has more power or influence can be explored. Another is cooperation, like them working together to solve a problem in the Dragon Ball universe.
One common theme could be friendship. Given their different roles in the Dragon Ball universe, a fanfic might explore how they become friends and support each other. Another theme could be power and respect, as they both hold significant power in their own ways.
One common theme is power growth. Goku is always seeking to get stronger, and in fanfictions with Female Beerus, she often challenges him in new ways, pushing his limits and leading to his power growth.