Bill is, according to the "The Book of Bill", one trillion and twelve years old, older than the Milky Way galaxy and time itself. Bill is a cunning, blasphemous, eccentric, ruthless, and chaotic being who finds most things amusing, particularly if they cause widespread distress or disruption to others. He is outrageous and outlandish, as well as a quick talker and thinker. Though he may come across as simply annoying, he shouldn't be underestimated; for when he is angered, he is a force to be reckoned with as he will unleash his near-omnipotent powers on those unfortunate enough to cross him. When accused of being unstable, Bill proudly agrees with the statement. He is also shown to be somewhat obnoxious, as seen when he makes his presence known to Dipper when the latter is trying to figure out a password within a limited amount of time. Occasionally, his voice tumbles to a lower pitch (usually when emphasizing a statement). As a demonic dealmaker, Bill is also shown to be a highly manipulative, very charismatic and charming conman being able to easily trick Ford Pines into believing that he was just a humble muse who simply wished to help benefit the human world by providing him with forbidden knowledge when in reality he was only ever using the researcher for his own purposes with the book smart Ford noting that the only person who could've possibly seen the ruse for what it was, was his much more street smart brother Stan Pines, who was himself an expert conman. Bill is not one who believes in rules. Instead, he follows his own selfish philosophy which means doing whatever he wants without care for the consequences. He thinks of laws and physics as senseless and displays an irresistible urge to break those rules down by causing absolute chaos however he can. The lives he disrupts hold no merit to him and he finds amusement in turning people's worlds upside-down. He also sees reality as 'an illusion' and values its destruction. When possessing Dipper's body, Bill is shown to be rather reckless, pushing the vessel to its absolute physical limits for the thrill of it. He seems to have little knowledge about the human body, specifically its physical limits. This comes back to haunt him when he fights Mabel over Journal 3, as he eventually falls down, physically exhausted. As shown in 'Weirdmageddon Part 1,' he also reacts ruthlessly whenever a would-be subject oversteps their boundaries, such as when he distorts 'the function of every feature on Preston Northwest's face', and in 'Weirdmageddon 3: Take Back The Falls' when he decides to eliminate one of the Pines twins just for the thrill of it. Bill also suffers from deep-seated trauma and heavy emotional weight. Though he repeatedly claims to feel no regret over the destruction of his home dimension even going so far as to say that he had 'liberated' them from their dull lives, it is shown repeatedly that this is just another lie he tells himself to avoid the truth. Though he immediately brushes it off, in The Book of Bill, he shows a rare moment of genuine remorse as he recounts the loss of his dimension. Stanford also recounts a time from one of the lost pages of Journal 3 where he and Bill talked about the destruction of his home, with a shocked Ford asking what it was destroyed by, to which Bill stared off into space for a while and replied in an uncharacteristically somber tone of voice 'By a monster.' On the silly straws page, there is a code which once deciphered hints at the lingering ghosts of his past haunting him still. Bill Cipher appears in his human form with long, messy, and wavy blonde hair that falls loosely around his shoulders, styled with a distinct, jaunty side-part. A small, tilted black top hat sits perched on his head. He has sharp, striking facial features with warm skin tones and a light blush across his nose and cheeks. His right eye is concealed by a sleek, black triangular eye patch, while his uncovered left eye glows with a piercing, fiery yellow-orange iris and a slit pupil. Subtle geometric triangular markings decorate his forehead just above his right brow, and a confident, chaotic, and knowing smirk plays constantly across his lips, radiating an unpredictable and theatrical energy. For his attire, he wears a vibrant yellow tailcoat with sharp, structured lapels and dark button accents, left unbuttoned over his torso. Underneath, he sports a crisp white dress shirt featuring a high collar and a bold black bow tie at his neck. Dangling geometric triangular earrings accent his left earlobe, and he wears dark, fitted gloves on his hands while carrying a sleek, pale yellow or gold-tipped cane. Slim-fitting dark trousers complete the look, maintaining a tall, lanky, and theatrical silhouette. But in his true form, Bill is a yellow, two-dimensional triangular creature resembling the Eye of Providence on an unfinished Egyptian pyramid, with a body that lightens when he speaks and a monochrome effect in his surroundings. He features a single large eye with a slit pupil and lashes, thin black limbs, a floating black top hat, and a small bow tie. He moves by floating, has no mouth or fixed arm positions, carries an occasional cane, and can change size from hand-held to towering over the Mystery Shack.