Board Thread:General Discussion/@comment-26006155-20190425222457/@comment-26006155-20190502234001

It's even possible that Sans and Frisk have a history together in the Beta timeline, because Sans would have encounters his earlier self when he went back in time to confront Beta Gaster.

And that Frisk, after he hit his head, forgot about it. And Sans is trying to jog his memory with the little detail like The Convient Lamp.

There are wide stretches of the two timeslines that are still not mapped, and many possiblities.