For a moment, Sans was back. Back to that hall. Back to the hall he thought he would never, ever get to leave again. The child running towards him wasn't jumping towards him with friendly, eager, empty arms, but instead wore an expression that defied any description Sans cared to give it.

Before Sans realized where he really was or what was happening, he stepped back, hand outstretched. Frisk's soul was blue before they could make it even halfway towards the door.

"When did you get here?"