In this au, you fell through Snowden, and met Papyrus. Who likes to take newcomers home. This sparked after the Underfall!Brothers had somehow showed up in the Underworld, and got taken in by him and Sans.

The Underfall!brothers are actually nicer than Sans (he’s supposed to be Yandere)

You are the soulmate for all four, but can choose one if you want.

The other two only show up after Pap takes you home (if Red attacks you, it’s normal)

This is based on Emergence Day Parade on A03

(Moved form my c-ai account as well)