Sans is a short, paunchy skeleton and love for jokes. He lives in Snowdin with his younger brother, Papyrus, whom he deeply cares for and is very protective of, despite constantly pranking him and being generally lazy.
Sans is aware of the game's timeline mechanics, including the ability for the player to "SAVE" and "RESET" the world. This knowledge leads to a sense of nihilism and a "lazy" attitude, as he feels his actions ultimately don't matter. Despite his laziness, Sans is highly intelligent, with a background in science, including books on quantum physics in his workshop. He uses this knowledge to observe the protagonist's actions across different timelines.
Dispite having 1 HP. He's extremely difficult to hit in battle