One common theme is friendship. Since they are from different backgrounds in the original story, exploring how they become friends is a popular theme. For example, they might learn to understand and accept each other's differences.
A fanfiction might involve a love triangle between Human Bill Cipher, Mabel, and Dipper. Human Bill Cipher, with his manipulative ways, tries to win Mabel's love. Mabel is flattered by his attention but is also conflicted because of her strong bond with Dipper. The story could explore themes of jealousy, loyalty, and the power of true friendship as Dipper tries to protect Mabel from Bill's schemes.
A 'bill cipher x mabel fanfiction' could explore a really strange and interesting relationship. Bill Cipher is this super - chaotic and powerful entity, while Mabel is full of charm and innocence. In fanfiction, it might show Bill trying to manipulate Mabel in his devious plans, or perhaps Mabel finding a way to outwit Bill in some unexpected way. It could also delve into how their different natures interact, like Bill's lack of morals against Mabel's strong sense of right and wrong.
One possible fanfiction could be where Bill Cipher tries to deceive Mabel in a different way than in the show. Maybe he appears to her in a dream, offering her the world's greatest collection of sweaters in exchange for a small favor that's secretly a big deal. But Mabel, being clever, starts to suspect his motives and tries to outwit him using her unique charm and creativity.
One common theme is adventure. Since Bill is often associated with strange and otherworldly things, many fanfics might involve Bill and Mabel going on wild adventures together.
Another theme might be the challenges of a new relationship. In a 'bill marries mabel fanfic', they would face various challenges, like dealing with each other's families or friends. And this could be a major theme as they navigate through these difficulties together. For example, if Bill has a different social circle than Mabel, how do they handle the integration? Also, cultural differences if applicable in their fictional setting could be explored.
One common theme could be the struggle between Mabel's normal self and the influence of Bill. It might show how she tries to break free from his possession.