USE LANGUAGE TO BE UNDERSTOOD. First and foremost, the purpose of speaking is to communicate ideas. If a character is fluent in both English and Thai, but her listeners understand only English, she will not toss in a Thai word here and there. If someone did that in real life, we'd think they were just showing off their knowledge. And here's a big surprise: that's how it comes off to the reader too -- like the author is showing off some language they picked up on their trip around the world.
THINK LIKE THE CHARACTER. What if the character ISN'T fluent in English? In that case, there will be words for which the Thai (or other language) comes to her mind first. Speaking fast, she may correct herself, which not only sounds natural, but gives you a natural way to translate what she says:
"Come on! We have to hurry to catch the rotfai. The train."
If her listeners are also bilingual, even only a little, she may not correct herself at all. In this case, you'll have to provide the translation some other way, either through direct telling or (better yet) through context. (Assuming you need the translation at all. Sometimes it just doesn't matter.)
She clapped her hands. "Children, our guests will be here soon. Gep your toys. Reoreo!"
DON'T MAKE THE READER READ UNINTELLIGIBLE GIBBERISH. I once read a novel in which the villains occasionally spoke in Vietnamese. It was cool except when the author strung together a long sentence of Vietnamese phonetics. It was pronounceable I guess, but pointless; I don't understand Vietnamese nor did any of the other characters. It felt like the author was just showing off how much Vietnamese they knew. Take a look at these two examples (with Thai, of course):
The door flew open with a bang. Four masked men ran in, guns pointed at Bernice and her family. "Lukkheun!" one of them shouted. "Lukkheun diawnii!" She didn't know what they were saying, just put her hands on her head and sobbed. "Tah mai lukkheun diaw ja ying kah man. Ow mai! OW MAI!"
This isn't bad, but by that last sentence probably most of you aren't actually reading it anymore. Even if you did read it, you might wonder why since you gained no meaning from it (unless you speak Thai of course, in which case I kindly refer you to this post). But we can change it so it still conveys foreignness and Bernice's terror, without forcing the reader to slog through a bunch of meaningless phonetics:
The door flew open with a bang. Four masked men ran in, guns pointed at Bernice and her family. "Lukkheun!" One put a gun barrel to her mouth, shouting in a language she didn't understand. She didn't know what to do. She put her hands on her head and sobbed, but it only made him scream louder. What did he want from her?
PUT FOREIGN WORDS IN ITALICS. This goes along with not making the reader work. Italics signal the reader that these are words they don't necessarily have to know (also that they're not typos). This even goes for words that you think everybody should know.* A good rule of thumb is if it's not in the English dictionary, italicize it. For example:
"You're hungry? No problema, I'll pick up some burritos."
* I've noticed this problem especially with Californians (like me) who assume everyone took Spanish in high school (like me). Also with British authors and French. I'm American, I don't speak French!
USE FOREIGN ACCENTS SPARINGLY. If English is someone's second language, they may have an accent. You've probably read stories where a character's accent was annoying or really hard to read. It's hard to do right, but the general rule is: be subtle. Imply the accent rather than hit the reader over the head with it.
Also, think like the character. If the character's first language does not have definite articles, they may drop them when speaking English. A common Thai mistake is to get 'he' and 'she' mixed up (although that could be confusing for the reader -- it is for us). When I'm playing a game with my daughter, she sometimes says, "You're going to win me," because that's how the word for 'win' is used in Thai (they have no separate word for 'beat').
It helps to know an ESL speaker, or to know a foreign language so you can work out how the character might process English. If you're not sure though, then don't do it. The character can just use simple words and sentences, with the occasional foreign word tossed in where appropriate.
So to sum up. If you're using foreign languages in your fiction:
- Don't do it just to show off.
- Be intentional; think like the character.
- Be subtle.
Got any other tips? Annoyances with how some authors handle it? Tell us about it in the comments.