However, in the middle of that, is it appropriate to have the second speaker give an unidentified reaction while the first speaker continues?

No.

There is a story about Hemingway. He was speaking to students who had been reading "A Clean Well-Lighted Place." There is a long run of alternating dialogue between the Old Waiter and the Young Waiter and it becomes very fuzzy as to who is speaking. Who is speaking is important to understanding the scene. A student asks Hemingway to clarify. Hemingway looks at the dialogue and days, "It's perfectly clear to me."

Yeah, for long-running scenes, it's nice to have a good memory of who's on first, but even in lit, a reminder every now and then during a lengthy conversation between two people is pleasant, if not somewhat necessary.

IOW, FU H.

Aw, io9 really likes us. See the last lines of the article.

Out-smolder the Winchester brothers? Unpossible. I'm going to put John in there as well. Smokin'!

::nods::

Actually? Both Johns have a pretty good smolder on. IJS. Adam's a cutiehead, but he still gotta work on the smolder.

I guess I'm going to have to be the first person to stand up for the angels. Castiel can smolder in my personal space any time he wants (and he can bring Balthazar and nine of his closest friends).

Heat, this show is not short of it.

I hope we see Balthazar again. He was excellent.

Oh, if we're talking non-Winchester smolder, I gotta vote Victor. Can we resurrect him for reals?

The menfolk are mighty fine on Supernatural. Even if Sam's hair is unfortunate. (I miss season 4 Cas hair, it's too short now. I'm holding out hope that they let it grow in the second half of the season).

Oh, Victor, so fine. That was so much story potential cut down in it's prime.

Sam's hair is epically fine right now. Back off, or I will have to cut you.

Robo Sam cartoon. I have been spending forever on deviant art recently. It's illuminating.