However, after his skull got broken and a part of his magic was taken by the now insanely violent Undyne, something within Sans changed. Sans instigated a new rule by Undyne, where humans who fall down are to be consumed for survival. After this, Sans was no longer the joyful skeleton he once was. According to the bunny, despite the rule he himself implemented, Sans has not eaten anything for 7 years, which then led to him losing his kindness, along with his sanity.
After many years of hunger