He feels Aziraphale coming from the other side of the Commons. It comes with a certain kind of tingle, a prickle in the hairs on the back of his neck that would have been a warning once upon a time but was now little more than an indication of a not-so-opposing force in the vicinity. All angels felt a little different when they came near him, and he could always tell the difference.

That's why he doesn't look around, but rather waits until he can see the faint outline of Aziraphale's reflection approaching from behind him. He shifts the position of his shoulder against the frame of the window.

"Funny to think about, really," he says after a few minutes of companionable silence. He rarely feels uncomfortable around the angel anymore. "Humans might achieve this one day, or something like it, because of what we did."