The final door has no handle. It says only: keep going down. The reader scrolls, lending them a little time.

ONE UNWRITTEN LINE

ELI: I carry the left. LIN: I carry the right. ELI: Who carries the middle? LIN: The person reading.

When the last sentence passes through the blank, the door remains where it was, yet blocks no one. The story does not fill it. The story learns to pass through.