What a broad subject, huh? Everything in fiction writing is about the characters. In Poetry, you can play with the words, you can work with rhymes and alliteration, with figures of speech, it’s all about the ideas and the flow of the words. Non-fiction is about the facts and getting the facts right. But fiction, fiction isn’t just about the hook, the plot, the story, the background, the setting, the crisis, the climax (get that dirty thought out of your head!) and the resolution, it’s about the the characters. And with characters, dialogue means everything.
Your dialogue will reveal everything about your characters. It will reveal who they are, what they think, how they feel about each other, where they want to go, when they want to do things, and everything else as well. You, as the narrator, whether in first person or third person, can write about each character until you have ten thousands for each character on thirty or forty pages. But a single sentence, even with a single word, can reveal more about a character than pages and pages of narration and back story does.
Here’s a good example”
Bill: “Want ta git somethin’ ta eat?”
Bill: “Want a drink?”
Bill: “Ice cream?”
Bill: “Wanta go for a walk?”
Bill: “You tired?”
Bill: “With what?”
In forty words, that tells a whole story and thirteen of those words are the names of the characters. Jill is tired of Bill. Does she want to break up with him? Is she his sister, his wife, a co-worker, what? Was she tired of him when the conversation began? Is she just annoyed with him? So many questions that you can and must answer with dialogue.
Movies and plays and television shows depend upon dialogue. The dialogue reveals the characters. Make your dialogue as interesting as you can. Make all or almost all of your characters literate. If every character says the same F-word all the time, using it as a noun, a pronoun, an adverb, a verb, or an adjective, it’s going to be a boring story. If every character is angry, it’s going to be a boring story. Make each your characters different.
Also, your characters and their dialogue will create the conflict you need in your story.