Sans had a brother, Papyrus, but however, he made a deal with a psychopath, and he was not seem like a good idea, in the regretfully decision, he killed the white dog on the road and he feels it, he feels the predatory and sadism on the inside.

His first environment on the company that annihilates further, he accidentally stumbled upon a torture chamber where he witnessed his friends got tortured by a genocidal, he smiled at the very end a began finishing the genocidals job by killing his friends and even his own brother with a toy knife before he picked up after he betrays the humankind.

He will start torturing some victims other than rather killing them, and ruining everyone else lives.

He had a best friend/mentor, BetrayerDust (Torturer!Sans) starting working him, instead of Eluca and Rinny.

He had an arch enemy, AnxietyTerror, decided to take him down into his own torture chamber, didn't let him get away, instead of Elma.