after many genocide routs, the underground scientist WD gaster had enough. he found sans the skeleton, already powerful, and taught him. how his friends were being slaughtered over and over again by the human. they joined forces, and sans vowed to fight until his last breath. the human came across this new, more motivated sans. but this time. . . he has Gaster; likely the most powerful monster in the underground. sans gets his ass kicked, and now, Gaster decides to take matters into his own hand