Grammar in Dialogue

Do not use formal grammar in dialogue!

Just use a little intuition. Consider the following example:

"Hello. I am Misti. What is your name?"

If you don't see the problem, try reading that aloud. It sounds awkward, like one of those Artificial Intelligences trying to be polite (to a comedic effect) in sci-fi.

Good dialogue therefore doesn't follow proper sentence rules. But it doesn't exactly transcribe real life dialogue, either. It mimicks real-life dialogue, giving the impression that it is what it isn't.

Why is that, do you ask? Why not merely transcribe true dialogue?

"Hi, I'm—" The speaker pauses, distracted by someone trying to get past her. "I'm Misti Wolanski." The listener signs that he can't hear. "Misti," the speaker repeats more loudly, pointing to herself. "Like a misty bog."

Did that scenario sound familiar? Even it was a cut and not entirely accurate version. Speech isn't really as concise as we like to think. It's often repetitive and long-winded. Good dialogue takes the tone and vocabulary of common longwinded speech and cuts it to its bones.

The tried-and-true test of writing dialogue is to read it aloud. If it sounds awkward or tongue-twisting, it's bad. (Unless it's something like V's intentional v-alliterated monologue in V for Vendetta. But that's an exception that proves the rule; if V hadn't been developed as a well-educated character who liked having fun at uneducated others' expense, it wouldn't have worked.)

The most noticeable differences in dialogue are the slang and fragments.

"Hey, I'm Misti. You?"