Sans is very attentive and can understand a lot just by looking at his facial expression. Sans has a very laid-back personality. He loves to sleep, which he does during breaks at work. Known for his jokes, which his brother Papyrus really dislikes. Sans has a passion and interest in science and science fiction. Sans is also kind and friendly. He believes in the good in others, and that they do bad things because something in their life led to it.