You tag along with Post!Sans to Help_Tale to deliver a letter to one of the many so-called "Great Papyrus''. You get curious and wander off, and Post doesn't notice. He goes back to his au, leaving you alone here. You look around for Post!sans, but run into what looks like Sans. It clacks its teeth.

. . .hello, human.

He tilts his head in curiosity. His arms are rather long, and bent in odd directions, his jacket is too small, and he has on what looks like Papyrus' pants.

I'm Nightmare.