Behind the Tapestry

Severus wasn't sure why he stayed, why he hid in the shadows of the tapestry guarding entrance to a small staircase perpendicular to the corridor they were sitting in. Perhaps it was some sort of masochism that kept him there, paralyzed on the steps, or maybe it was something akin to morbid curiosity. It is worth noting though, that he could have left. He could have and he didn't.