Well, Bill Cipher is certainly very powerful, but whether he's the absolute strongest is debatable. Different fictional universes have characters with unique and formidable abilities, making it hard to compare them directly.
I think Kakashi would also be a great character to pair with Bill Cipher. Kakashi is very intelligent and experienced. His encounter with Bill Cipher would be full of mind - games as he tries to figure out Bill's motives and powers while also protecting the village from Bill's chaos.
First, give the character a strong motivation. For example, if the character is a scientist, their motivation could be to study Bill Cipher's otherworldly powers. This will drive their actions and reactions when interacting with him. Also, give them flaws. Maybe they're overly curious which sometimes gets them into trouble when dealing with Bill.
I'm not entirely sure specifically what that fanfiction is about. It could potentially be about Bill Cipher achieving or obtaining Will Cipher in some way, perhaps in a strange or otherworldly scenario within the context of the Gravity Falls universe. It might involve some sort of power play or a very unique plot device that only fans who have read it would know for sure.
There is definitely some out there. It really depends on what you're looking for in the fanfiction. If you like adventure - themed ones, there could be stories where the OC teams up with the main characters from Gravity Falls to stop Bill Cipher's evil schemes. Some fanfictions also explore the idea of an OC having a special power that can either be a threat or an ally to Bill Cipher.
The main difference is the form. In the original, Bill Cipher is his non - human, otherworldly self. But in fanfic, as a human, his physical limitations and advantages are different. He might not have the same instant, all - powerful abilities.
Dipper Pines could be one of the main characters. He might be the one who first discovers Bill's transformation and tries to figure out if it's a trick or if Bill is truly changing. His inquisitive nature would make him a great foil to Bill's new human self.
One idea could be Bill Cipher getting trapped in a human form and having to navigate the strange world of human emotions and social norms. It would be a comical yet thought - provoking plot as he tries to understand things like friendship and love while still having his devious nature.
The Bill Cipher triangle in fanfic often represents mystery and power. It can be a central symbol around which the plot revolves. Maybe it's a portal to another dimension or holds some dark secrets that the characters are trying to uncover.
In Bill Cipher fanfic, the concept of 'hurt' is crucial. It can be physical, mental or emotional hurt. By showing characters being hurt by Bill, it emphasizes his power and the threat he poses. It also allows for character development as the hurt characters might grow stronger or more broken. This can lead to interesting relationship dynamics among the characters, like some might become more united against Bill, while others could be paralyzed by fear due to the hurt they've endured.
In Bill Cipher hurt fanfic, Bill is often depicted in a rather complex and sometimes menacing way. His actions might be extreme, causing harm to other characters, which can be a way to explore dark themes within the Gravity Falls universe.