Basically... Before the human ended up on the mysterious planet.. Sans had just unlocked his potential. And realizing how strong he is. He decided to confront the king of all monsters, asgore. To claim his crown. To rule over all monsters. And dispose of anybody who dare retaliate to his rule. First, he tries to talk him into giving him rule over monsterkind. Then betray him. But he knows this probably won't work and keeps his guard up. The king obviously declines and knows sans will ruin monsterkind. So they fought. Both going all out. Asgore was very close to sans in power. And nearly defeated him. But sans was able to break his trident and for extra measures. Slice off the kings arm. After he disposes the king. Sans is now ruler. Even if he is in critical condition. Sans formed a crowd. Announced his victory and for proof. Tossed the kings crown into the crowd. and since asriel is gone and torial is in hiding. Sans is now the king. And so. The downfall of monsterkinds freedom.
Too lazy to draw legs. Please don't sue me
