Evidence includes the quantum physics book, workshop, his relationship to Alphys, affinity for science, his inexplicable ability to teleport and his timeline research. Regardless of the human being partially or wholly merciful, Sans tells them that if 'the old lady' had not made him promise to protect them, ' (they'd) be dead where (they) stand.' During the Genocide Route, he does everything in his power to kill the protagonist, even faking mercy. Though Sans is usually agreeable, he can become eerily serious to emphasize a subject. He is also observant Sans reads the protagonist's expressions and can often tell when they have already done certain tasks. In a Neutral Route ending where Papyrus or Toriel is alive, Sans omits the protagonist's slaughter to either of them. Even if the protagonist killed people that were close to him, Sans refrains from broaching the topic until the Last Corridor.

Sans has informed Big Mouth about 'all kinds of incredible foods,' yet Big Mouth comments that 'he always orders the worst burger off the menu.' Although Sans hates making promises, he respects Toriel's request to watch out for any humans. For example, Sans is a regular at Grillby's, and the monsters and Royal Guard dogs treat him kindly. Дespite Sans being apathetic towards his own life, he is considerate to those he cares for. He enjoys making others laugh in general, as he also performs at the MTT Resort as a comedian. Sans is also fond of making the occasional low-brow puns. He is not above utilizing his teleporting or other magic for practical jokes either. Examples include Sans 'selling fried snow,' using whoopee cushions, sharing an unscrewed ketchup bottle, and eye paint on a telescope. His antics range from an assortment of illogical, juvenile, and slightly inconvenient pranks. Sans primarily acts this way towards those he is in good terms with. Conversely, he suggests that this knowledge could be ' a poor excuse for being lazy.'

His laziness is a combination of fatalism and apathy, as he is aware of timeline resets. Sans is laidback and flippant, often sleeping on the job and taking breaks. When Sans uses telekinesis, his left eye flashes light blue and yellow, the colors for patience and justice, and his right pupil disappears. He has white pupils that disappear when he is serious or angered. He wears an unzipped blue hoodie, a white shirt, black shorts with white lining, and a pair of slippers.

Sans appears as a short, paunchy skeleton with a wide toothy grin, glove-like hands and large eye sockets.

Just shapes and beats all bosses images