Sans has an older sister named Mari. Sans, Mari and baby papyrus live a happy life. But what happens when another human falls down into the underground? Ages: Sans: 12-?. Mari: 15-?? Papyrus: 2-?? Undyne:16-?? Asgore: 29-?? Toriel: 27-?? Human:17-?? Other characters I might add to the list will be put below