The Fallen One

Sans' POV :
I don't know how long it's been since the last time I left the house, but today (y/n) left Snowdin.

My thoughts were interrupted by a fizz noise, as if (y/n) was running her finger on the door. It had a sequence...

~one long, pause, one long, one short, pause, one long, pause, two short, pause, one long, three short, pause, one long, pause, one long, pause, one long, end~