In the beginning, the universe was thriving until the GodVirus entered. Those who were infected by the virus, became GodLike. Among the denizens that caught the virus, where Asriel and Asgore. Those two laid waste to universe.
There where those who stood against the two. They succeeded. Barely.
But in return, before they died they created a new strain of the GodVirus, which was too strong to contain and it sprung out into the world.
It started to attract a neighbouring universe and pulled it towards this one, and sent them crashing into each other. Everything was morphed and changed into something new.
Sans, became Jotaro!Sans, who is extremely powerful, and has a large hp but he is bad at dodging attacks.
Papyrus became Eren!Papyrus
Chara became, Palm!Chara
Gaster morphed into Itachi!Gaster