Take a conversation from a story you’re working on–preferably one with some tension to it. If you don’t have such a conversation to work with, write down as much as you can remember of an actual conversation you had recently; you don’t have to stick too closely to reality as long as you get the gist of it.
Make a list of all the ways in which this conversation could have gone (or could go) wrong. What misunderstandings could occur? What impasses could the characters reach? What could someone say differently that could change the entire meaning of a question or sentence? What past context could cause the conversation to take on new meaning?
Write a new version of the conversation in which things take a drastic turn for the worse.
So many good plot twists hinge on misunderstandings, miscommunications, arguments, anger, and so on. Tension between people can be displayed perfectly in a good conversation–both by what gets said and by what doesn’t get said.
One of the television shows I watch prefers to focus on episodic plots, with character development a comparatively small thing displayed around the edges of the show. Recently one of the characters had an argument with his wife in which he accused her of various things. At first I remember thinking that this was rather out of the blue, since we hadn’t seen much of their relationship. Then I remember thinking how brilliantly the small snippet of conversation said so much about their relationship. Things don’t instantaneously get to the point of accusations–clearly this isn’t the first thing to go wrong between them, and it hasn’t been the first point of trouble on the show. There were also other things in the content of the conversation (and the context of the show’s history) that showed that the misunderstanding might not have occurred had the wife known her husband better. In just a short conversation, with a bit of the show’s history to back it up, a great deal was said–and a great deal happened.
Think about ways in which you, too, can serve so many functions with such a short piece of dialogue.