It's one of the biggest problems plaguing fiction — and it seems to hit genre fiction especially hard sometimes: the characters who all sound exactly alike. How do you keep your characters from all having the same voice?
This is something I've struggled with in my own fiction, and it's a much messier problem than you would think. Even when you feel like your tough woman space captain and your sensitive young astro-biologist are incredibly well drawn and full of character and neuroses, and nobody would ever imagine they were the same person. And then you're looking over your novel for the tenth time, and you realize that they're all sounding absolutely identical.
It makes sense, in one way — your characters are all aspects of you, after all. They all came out of your head, unless you based them on your friends or other fictional characters. (And even if they're based on someone else, they're still your creations, when it comes down to it.) You're speaking through their mouths. But that doesn't mean they're doomed to sound like you, or like the same person. This is totally a solveable problem.
Here are some solutions to the issue, ranging from least crude to crudest. If the least crude solution works for you, then you don't need to worry about the rest of them — but I've used all of these methods at various times, and there's no shame in using tough measures on your characters.
1) Listen to how people talk. I have a feeling this is what "real" writers do. Don't listen to how people talk on television or in the movies — go to a bar or cafe and just listen to the conversations around you, and try to hear how people are speaking. If you can write down snippets of people's conversations without being a total creep, then do that. V.S. Pritchett writes about doing this when he was a young writer — and one of those snippets of conversation even found its way into a short story that he later published. Try to get a feel for the rhythms of conversation, and the way different people form sentences. Bottom line is, if your characters all sound the same, then they're not sounding like natural dialogue at all.
2) Try to "hear" your characters' individual voices. This is not really cruder than the first one, actually. If your characters are really that vivid in your head — if you really feel like they're real, breathing people that you've brought to life inside a living story — then you should be able to hear their voices. And they don't just sound different because they choose different words to express themselves — they are saying different things.
Say Space Captain Starjumper makes lots of definitive statements, because she's got lots of points to get across, while Astrobiologist Second Class Sparrow is constantly raising tentative half-questions. Maybe Captain Starjumper has an undercurrent of insecurity, and that's part of why she has to make sharp statements all the time. And Sparrow really knows more than he's saying. The way in which people say the things they say also provides the reader with more information.
3) Realize your characers are not talking to you, or directly to the reader. Unless you're really doing some kind of post-modern fourth-wall-shredding exercise, your characters are talking to each other. And think about what kind of reaction your characters are hoping to get when they say something. Not the reaction they actually do get — it's too easy to jump straight to that — but the reaction they expect. Fine, Navigator Angstrom's revelation that he turns gay whenever the ship is in hyperspace meets with a stunned silence. But was Navigator Angstrom hoping for a stunned silence? Was he trying to provoke an angry response, or some kind of accepting, reassuring statement? Was he trying to guilt-trip the captain for making so many hyperspace jumps lately? It sounds obvious, but it's often hard to remember: the response you're hoping for shapes the way you talk. And every one of these characters has a script in his/her head for how this conversation is going to go, whether it goes that way or not. You, as the author, know the way you want/need for the conversation to go, but you need to know what the characters want/expect as well.
Update: Zack Stentz, writer on Terminator: The Sarah Connor Chronicles and Fringe, points out another helpful way of looking at this: "Every interaction between two people is on some level a negotiation for status." Remember that, and your characters' speech will automatically get richer and more interesting. Apparently this advice originates with Terry McNally, co-writer of Earth Girls Are Easy.
4) Try giving each character a few unique verbal tics, or habitual words. Maybe Captain Starjumper says "I declare" a lot, in between all those declarative statements she makes. (Okay, bad example.) Maybe Navigator Angstrom makes lots of puns, or tosses lots of sarcastic jokes into the end of every comment. Give
each character a few habits of speech, and maybe after a while those props will help you hear each character speaking differently. You may even be able to go back and take out some of these tics, if they get too repetitive, and if the speech around them has started to differentiate itself from the rest.
5) Go one step further, and give them catch phrases and stuff. This worked for Dickens, after all. A lot of Dickens characters basically have the same verbal habits over and over — the most famous of these, of course, is Mrs. Malaprop, who always uses words incorrectly, and gave us the term malapropism. (Update: Various people have pointed out this is not true. Sorry about the mix-up. I've read almost every Dickens novel, and somehow I believed this incorrectly. My bad!)
But it's true of a lot of minor Dickens characters. And especially if you're going for humor, there's nothing wrong with having a character who comes out with variations on the same funny line on several occasions. Maybe your astrobiologist character constantly states the obvious, but prefaces it by saying, "I have made a cunning observation."
6) Realize that you may have, at most, three or four character "voices" and refine those. As regular readers of this blog know, I utterly, unreservedly love Joss Whedon. But he is a perfect example of a writer who has a few voices that he uses over and over. There's always the stilted British person (Giles/Wesley/Adelle), the funny, quippy nerd (Xander/Topher/etc.) and the lost/crazy girl (River/Echo/Fred/etc.) And the amazing thing is — those characters are all wildly individual and have tons of depth. You would never mistake Giles for Adelle, even leaving apart that she's way prettier. (Well, somewhat prettier.) Whedon may have a few basic voices that he reuses over and over again, but he finds other ways to make his characters unique and distinct from each other. He's also worked, over the years, to refine each of those voices and make the most of their strengths.
7) Vary your sentence lengths, and play with punctuation. If all else fails, try this. In real life, some people tend to speak in longer sentences, others in shorter ones. (Actually, we all vary our sentence lengths all the time, but our average sentence lengths vary quite a bit.) There's nothing wrong with just deciding arbitrarily that Captain Starjumper's average sentence will be five words long, while Navigator Angstrom's will be twenty. Also, you can try giving one character lots of emdashes or colons in his/her speech — but do this sparingly, and only for one character. In my new fantasy novel, I have one character who includes lots of parenthetical statements, and I put those in actual parentheses. But I made sure to avoid any funny punctuation games with any other character's speech, so it didn't start annoying the reader too much.
8) Adjust the French/Anglo-Saxon mix. Those of us who write in English are lucky — it's actually two languages in one. (Plus random language detritus from a dozen other languages.) We're speaking a mixture of Anglo-Saxon and French, the language of the Normans who conquered England in 1066. And just as the Enterprise's engines are a mix of matter and anti-matter, your speech is a mix of French and Anglo-Saxon. And some people definitely use more words of Latin origin than others — it's often a badge of education and upper-class status to use lots of obviously Latinate words. So if all else fails, try experimenting with having one of your characters use more Anglo-Saxon words than the rest of them, or more fancy French words. Grab a dictionary of etymology and think about which words come from which language — you can give your characters a more Germanic or more French "voice" without actually making them speak a foreign language at all. You could also just try having some characters use more one- or two-syllable words than the rest, but this might be subtler and more fun.