We all do it. Even in an action-packed story, a character will pause at some point to speak at length about thematically significant things. Can I give you a few examples from my own books?
How about the time Aiden Tennant speaks in massive blocks of text about his life and his hopes and dreams? Mary responds now and again in order to break it up into digestible pieces, but it's basically Aiden downloading all of the thematic elements related to his character, in paragraphs such as the following (which proceeds after his confession about loving comic books and fantasy novels):
“So here’s the thing,” he said. “It’s gonna sound really weird, but the truth is I want all of that stuff to be real. Maybe it isn’t, but I want to believe in it, all of it. Nobody really believes in anything. My parents don’t believe in anything. They just breathe and eat and work. People like Kristen Grossman don’t believe in anything. Most of the people in Chesset go to church on Sunday and hear all of these wild, weird stories, but I don’t think they really believe a word of it. Some guy raised a staff and parted the ocean in two?” Aiden raised both hands over his head and waved them around, miming the old story and drawing more laughs from Kristen and the twins. He did not seem to notice them. “They don’t really believe that happened. They wouldn’t even want to live in a world where that kind of stuff was possible. They all want bland, they like bland. Not me. I don’t want a boring old world where all anyone ever does is grow up and work some awful job for no money and spend Friday evenings watching high school football games and recalling the so-called glory days until they die. They can keep that kind of life. Even if there aren’t any real aliens or wizards or magic or whatever, I want to read about them and pretend. It’s better than nothing.”
Or how about the time in The Vale of Ghosts when the mayor speaks for eight hundred minutes during a public meeting? What a perfect opportunity to clarify the nature of the conflict that will drive the rest of the novel. Here is the second paragraph out of six in which the mayor speaks:
“None of us can stand here and pretend we do not know,” the mayor continued. “What unfolded here two days ago is no mystery. Haven’t our ancestors passed down to us a thousand warnings about the vale beneath the ridge? The east, the west, and the south are closed to us. Only the land to the north is open. And not only did they warn us, but they left the ten relics of the prophet to protect us. Those who came before did all they could to keep us safe. Only deliberate disobedience, only mischief and defiance, bring trouble here.”
Then there's that time in Shadows of Tockland when David Morr gets a little speech from the ringleader of the circus about the nature of clowning and the different types of clowns, but really it's all foreshadowing the character conflicts that are to come. This long discourse is split up into reasonable chunks by David's brief responses, but otherwise it's just a huge thematic presentation of the novel itself:
“Onstage, whiteface clown is the boss. He’s the smart one, the bully, orders around the others. In our troupe, Cakey is the whiteface....whiteface clown is at the top. At the bottom, you’ve got the auguste,” Telly said. “The auguste clown is typically the dimwit character, the goofball, the idiot. Whiteface likes to slap him around, harass and threaten him, maybe toss a pie in his face. Karl is our auguste clown. He plays a character called Touches. Onstage, Touches takes a lot of crap from Cakey. That’s how it goes.”
“Karl is pretty huge,” David said. “He doesn’t have to take crap from anyone, I wouldn’t think.”
“Onstage and offstage, kid,” Telly said, waving him off. “I told you, don’t get confused. Now, in between the auguste and the whiteface, you’ve got the contra-auguste. Contra-auguste is typically trying to win the whiteface clown’s approval, caught in the middle, you might say. Annabelle is our contra-auguste, performing as Bubbles.”
“As for me, I’m the ringmaster,” Telly said. “The ringmaster’s job is to keep the other clowns bouncing off each other. A manipulator but never a victim. That’s me. And that ends lesson one. Now, did you write all of that down?”
Or how about that one time in Garden of Dust and Thorns where the protagonist screams the central theme of the entire book at another character for an extended length of time?
“You wanted to see the Garden in ashes, you’ll get your wish,” she said. “Revel in the death of the world, Sindaya. Revel in it. I tried to tell you. I pleaded with you, with you and with the others, pleaded with you to look around you, look at what you are destroying, and you would not hear it. Celebrate as your Lord of Dust and Sand and Misery eats into the Garden, celebrate and laugh as you pierce the bodies of innocent people who did nothing to offend you, whose only sin was living in the shadow of the wall. Wretches and pigs, all of you. Vile monsters!”
And that, folks, is what a nice monologue is all about. It's a chance for a character to just spell it all out without it feeling like a wall of dull exposition. Done right, readers won't even think outside of the character. They'll just be swept up in the scene.
To be fair, it doesn't always take a long paragraph to pull this off. It can happen in a sentence or two, such as the time in Dreams in the Void where the villain reveals the theme and plot in one short little statement:
“You’re…you’re already becoming like me,” he said. “Everyone is. There is only one mind now…only…”
Right to the point. Thank you, monologues.