Common Mistake #12 "As You Know, Bob" Dialog

One way authors try to work in information the audience needs is through dialog. This can work well if there is some believable context where one character knows something the other doesn't, so both that character and the reader can learn the fact or clue at the same time. There are two possible problems here, however, that one has to be on guard against.

The Dumb Blonde
Back in the bad old days of pulp fiction, it was fairly common practice to have the scientist hero explain how the warp drive works to the attractive heroine passenger whose primary role in such space operas was to say things like, "How does the warp drive work, professor?" You can imagine the reaction to this 1930's motif today. Sexism, racism, agism, etc is going to get you assassinated in reviews, so don't have a dumb anything in your story. If the only purpose of a character is so other characters can explain things to them, that's a fail. (Mirrors and pets count as another character if your protagonist talks to them more than once or at length.)

"As You Know, Bob"
It's okay to have the detective explain that the suspect was seen at the scene of a previous crime, because that's information the character who wasn't there couldn't be expected to know. As long as that dialog arises organically from the current scene, and doesn't interrupt the action, that's how to do it. But having one police officer explain police procedure to another police officer makes no sense. They both know that already so would no more explain that to each other than you explain how a toaster works to your family every time you heat bread. Explaining things other characters already know is only acceptable when deliberately portraying a character as mansplaining or afflicted with particular varieties of mental illness. Having characters say things they already know to each other drops the reader out of the character's point of view and therefore out of the story.

If you could add "as you know ______ (character name)" to any dialog between characters, all that dialog has to go.