So...dialogue craft thread ahoy!
Voice! Every character should have their own unique voice. Ideally, I should be able to guess who's speaking without tags.
Word choice, sentence length, cadence, exclamations & expletives, worldview, how they describe things, etc all factor in.
For instance, Amalia uses complex sentence structures, big vocabulary, likes to explain or analyze things in detail, swears mildly, etc.
This is something you have to listen for. Reading it aloud can help. A lot of it is developing an ear for it, but I know a few tricks.
If you're dropping a bomb in dialogue, give it white space around it so it really explodes in the reader's face.
Just watch out, because WOW is it easy to overuse the same beats all the time.
This is also how 99% of the wine in my books gets consumed, I'm not gonna lie.
Dialogue is often at its most amazing when there's more than one layer to it. What the character is actually saying, and then all the other stuff.
What they're holding back. Subtext, whether the character they're speaking to gets it or not. Irony or innuendo. Etc.
This can be especially tricky in FEELINGS dialogue. I get tempted to have characters tell each other exactly how they're feeling, but let's face it, most people are terrible at expressing their feelings.
As with basically everything else in fiction, dialogue is more compelling if there's something at stake, or some kind of push and pull happening in the conversation.
Consider stuff like power dynamics, too.
Like, if the Fearless Leader is describing the coming mission, maybe the tension is over whether or hero will get picked to go.
Just remember to listen, let the characters speak rather than putting words in their mouths, and let stuff (sometimes the most powerful stuff) go unsaid.