It’s Phantom Papyrus from Dusttale, Phantom Papyrus is a seemingly hallucinatory version of a deceased Papyrus that appears as a character in Dusttale, supporting Sans in his killing spree. Before Papyrus was killed by his brother in the 327th Genocide Route, he was a friendly monster who believed that anyone could become a good person if they just tried. Even after Frisk killed him multiple times, he still believed in them.