Ohmigod, you mean I actually did use it there? And not even in the scene I was thinking of. How . . . strange.
I still think it was used relatively early in another fanfic. I just can't remember which . . . although . . . I do have a vague memory of one where he's listening to Lois' heartbeat and hears something else, too. Three guesses as to what if you don't know. Was that the Heartbeat story already mentioned or another one entirely?
If that's not it, I have no idea. I just know it was already something being used, not a lot exactly but some, when I wrote Sanctuary.
And I think I have an inkling of where the idea comes from in the series. Can't think of the episode name at the moment but it's the one where she's trapped in a vault. Well, there were probably a couple of those, so it's the one with the invisible man. Whatever, he cocks his head and "listens" for a moment before diving in to rescue her. Seems like it was right after that that the concept began popping up in fanfics of all shapes and sizes.
