his Backstory: Initially a pacifist timeline, Chara would possess frisk and begin slaughtering monsters on the surface, sans would attempt to fight back, shielding an attack with his arm but this resulted in his hp going to 0. As he slowly turned to dust he noticed chara walking to a save star and with his dying breaths he intercepted the star and absorbed it into the hole where his eye socket used to be, only to then vanish. Sans would wake up in a void outside his au with nothing but himself. realizing he needed to get back to his world but was unable to, he then noticed a stinging feeling coming from his face. There was a giant yellow flame emitting from his eye socket. He freaked out at first but realized that the star thing he absorbed not so long ago was filled with past determination used by the kid. After a while of thinking he came up with the idea to ask for help to restore his world. So instead of asking someone from his world he went to another one not too far away. He went to UnderFell.blue where he would meet the aus sans asking him to help him to Save his world. This Backfires when after a squabble Fell.blue Sans tries to get out of helping Syno, but when he returns to his au he comes back to find everyone gone kidnapped by syno. With this synos blackmails Fell.b into further helping him