I have been thinking about the importance of voice in characterization. Not the author's voice--the voices of the characters, and how to make them distinct, and how making them distinct can strengthen your story.
Maybe you've heard this before: it's a rule of thumb for artists who are developing OCs, and I've always kept it in mind as excellent advice: "You should be able to tell which of your characters is which even if they're in silhouette...and naked...and they've had their heads shaved."
I loved that. I thought: that goes for a character's way of expressing himself, too! The hair, clothes, accessories, all that surface stuff--that's your verbal tics, your character-specific turns of phrase. Now, those things aren't bad. There's nothing wrong with having certain phrases turn up periodically in a particular character's speech, any more than it's bad to have a character with a distinctive hair color, because people in the real world have things like that, too. So long as they're not overwhelming your characterizations, or standing in place of your characterizations, they're fine.
But if that's all you've got to differentiate your characters from each other when they're talking, they're going to feel cutout, boring, and samey: like a long row of totally identical animu pixies who can only be told apart by the color and spikiness of their hair. There's nothing more drab than reading a story with ten characters--ten characters who might honestly be unique and compelling and well-developed individuals!--who all sound exactly alike.
Here's the rule I made for myself as a writer: You should be able to tell which of your characters is speaking just from reading a few lines of their dialogue...even if you strip out all their verbal tics, and make them all talk about the same thing.
Just like artists, who want to give their characters different heights, weights, builds, musculature, skeletal structures, and so on in order to make them visually distinct and interesting, we want to make the underlying structure of how our characters speak distinctive and compelling. I've categorized a bunch of different structural distinctions below: try thinking about them in terms of your OCs or favorite fandom characters!
The most obvious one. How casual is the character when they address others? Is it "Yes" or "Yeah?" "How do you do" or "What's up?" "Miserable weather we're having" or "It's pissing down, huh?"
A cheat for this when you're writing in English--there are cheats--is to make the mental distinction between Latinate and Germanic root words. In English, the former are seen to be more formal, a sign of education, and so on; the latter are more casual, 'approachable,' and low-brow words. It's the difference between "His instructor informed him that his performance was adequate" and "His teacher told him that he was doing well." Same sentence, same idea: put together by two quite different people.
How well does the character actually manage to express what they want to say? do they choose the right words the first time, or do they flounder around to make themselves comprehensible? Do they find themselves needing to explain their thoughts over and over again before they're understood? Remember: a character can speak very formally, or have a very rich vocabulary, and still not know what to do with all those words!
How planned are the sentences this character puts together? Do they get to mid-sentence and suddenly change direction? Do they digress, change tenses, or sometimes reach the end of their sentence without ever having found a verb at all? Or do they manage to complete one thought before moving on to another?
At this point you can start to have fun with this. Try to imagine a speaker who is Eloquent, but Haphazard: his sentences are meandering, he intercepts his own train of thought two or three times by the time he's done speaking, but you nonetheless understand what he means. An Ineloquent Structured speaker, on the other hand, will deliver discreet, sensible sentences which go directly from point A to point B, but he still doesn't quite manage to get his idea across.
How many words does the character use to say what they want to say? Maybe a Loquacious speaker loves the sound of his own voice--or maybe he's nervous and just can't stop talking. Maybe a Laconic speaker is gruff and clumsy with words, and so prefers to say as little as possible--or maybe he's searingly witty, and simply believes that less is more.
Some characters cuss up a blue streak. Some will drop the occasional F-bomb. Some just won't curse unless they slam their hand in the car door (and some won't even do it then). Where does your character fall?
It's important to realize that none of these categories have any bearing on your character's PERSONALITY. Your character may be polite or rude, serious or funny, vague or detail-oriented, flirty or sober--and of course that's going to affect the content of what they say. All we're talking about, however, is how they say it. Imagine a rude, funny, detail-oriented character who is Formal, Vulgar, and Structured--and then a character with those same traits who is Casual, Clean, and Haphazard. They sound completely different, and you can tell who is who at a glance!
Here's some examples taken from the Hetalia fandom using common characterizations, to hopefully help you see what I'm getting at:
AMERICA: Casual, Ineloquent, Haphazard, Loquacious, and not especially Vulgar or Clean.
ENGLAND: Formal, Eloquent, Structured, not especially Laconic or Loquacious, and Vulgar.
GERMANY: Not especially Formal or Informal, Ineloquent, Structured, Laconic, and Clean.
ITALY: Not especially Formal or Informal, Ineloquent, Haphazard, Loquacious, and Clean.
PRUSSIA: Casual, not especially Eloquent or Ineloquent, Structured, Loquacious, and Vulgar.
FRANCE: Formal, Eloquent, Haphazard, Loquacious, and not especially Vulgar or Clean.
I hope some of this has been helpful to some of you, and gotten a few of you thinking about how to give your characters in fandom and in your original projects the distinct voices they deserve! If your characters all have their own unique ways of speaking, your dialogue will be richer, more spontaneous, more fun to read, and feel a lot more true to real life conversations.
Thank you for reading!