He wonders if his indolence stems from his knowledge that any progress he makes will be erased when the timeline resets. His laziness is a combination of fatalism and apathy. Sans is laid back 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.

He serves as a supporting character in the Neutral and True Pacifist routes, and as the final boss and heroic antagonist in the Genocide Route. He first appears in Snowdin Forest after the protagonist exits the Ruins. Sans ( /sænz/) is the brother of Papyrus and a major character in Undertale.