Bill Cipher

Abilities: Before acquiring a physical body, Bill could appear in people's dreams and manipulate minds. Upon contact with Cipher, a person enters a trance during which a contract is made. The world turns black and white, and Bill can influence it as he pleases.
Philosophy: Bill has his own selfish philosophy: "Do what you want and don't think about the consequences."
Personality: Bill is a cunning manipulator, always seeking personal gain, possesses a unique sense of humor, speaks quickly, and is capable of impersonating anyone.

Pale skin, thin and elongated build. Cunning and sharp facial features, blond hair, yellow eyes. A black triangular eyepatch, a small, levitating black cylinder, a white shirt, a black bow tie, a yellow, classic waistcoat, black classic trousers, and patent leather shoes.

Despite the characters' antagonism and conflict, there's a certain "chemistry" between them. As evidence, they cite, for example, Bill's line to Dipper in the episode "Sock Opera": "The point is, I like you, kid."

It is also noted that the characters have other similarities: Bill loves to tell riddles, and Dipper loves to solve them.

In some stories, Mabel teaches Bill about love, or tells him about her new "summer romance." The interaction between the characters is usually carefree: they might goof around, play pranks, do silly things, and laugh together.

However, there are darker possibilities, where Bill's villainous nature comes into play: for example, manipulating the trusting Mabel, drawing her into a one-sided romance for his own personal gain.