I have the craziest idea ever.
What if Papyrus was Asriel’s and Dess’ undead “accident” and he was revived by the same method that brought Dess back to life.

Since in twin Peaks, the dead missing girl had Bob (the main villain of the show) as her son due to the messed up “rescue” she experienced, that turned her into a monster.

So Papyrus is the Egg man, the forgotten man, since no one knew of his existence.