I'm working on a piece right now for a contest in which the object is to write a story using dialogue only -- no narration, no attribution tags (he said, she said), no direction of any kind. Maximum 3000 words.
I'm using a previously written scene from an unfinished manuscript. Took out all the narration and attribution. It was really interesting to see everything stripped away, leaving just two voices. I gained insight into these two characters and noticed things I hadn't previously noticed.
For one thing, these two characters don't listen to each other (this was pointed out by someone who read the dialogue). For another thing, they're reluctant to let the other person in, to be vulnerable. That's something I already knew about them, but it reveals itself in this scene.
But something is missing at this stage. In any story, characters have to want something. It's not clear yet what these characters want. In fact, they are more telling of what they don't want.
The challenge, then, is to balance showing with telling. The dialogue can't be forced ("telephone dialogue," I call it, which annoys the crap out of me -- a way to let the audience know what the person on the other line is saying, "Why yes, Mrs. Peterson, Scotty did leave thirty pizzas at my doorstep... No, I don't know who's going to pay for them.... Yes, he most certainly is a little shit." and so on), but it also needs to give the reader everything he/she needs: what's going on, who are these people, what do they want, and what's stopping them from getting it.
In this case, I need to approach it as if the reader is sitting in a diner, and this couple is in a booth behind her, and she's eavesdropping on them. She can't see them. I've got to show emotion by inflection, which means I've got to use stylistic tricks (italics, elipses, em-dashes, etc.). I've also got to make each voice so distinct that the reader knows who is saying what, just as the eavesdropper would. And this eavesdropper needs to be riveted. It can't just be another argument between a couple. Like I said before, these characters need to want something. That needs to be made clear to the reader. And the reader needs to root for them.
I'm not there yet.
But I hope to be. It's a fascinating exercise, really. I'm not sure if I'm gonna use the scene I've chosen. There's another scene that comes before it that is more exciting (and poses a bigger challenge) because it takes place at a dinner party with seven characters -- wouldn't it be cool to master that!
So, I'm posing some questions to you, dear reader. What would be compelling dialogue to you? What would you write about? How would you meet this challenge? And what would you, as "the eavesdropper" want or need to know?