NEW THERORY!

First, the question: Where did Sans and Papyrus come from? If you talk to the people in Snowdin, you find out that the skeleton brothers just showed up one day. I personally think that they were created by Gaster as an experiment.

When Gaster accidentally got into the void, the skelebros were forced to care for each other. That's why despite they have different opinions, they get along fairly well.

And as for showing up in Snowdin one day, perhaps Gaster used to live there.

Once again a short chapter, but a chapter is a chapter. More soon!