(No spoiler disclaimers this time, but disclaimer link anyway for swearing.)
I don’t much talk about my own writing here, because honestly, I’m unpublished so no one gives a shit. (I do occasionally broach the topic on my Google+ page if you’re so inclined.) However, I had an experience a little while back that seems relevant.
I was working on a second-world fantasy dealing with multiple cultures, and though I’d done some initial brainstorming about the setting, I went ahead and started on the first scene. A page or two in, one character said “damn.”
A little voice popped up in my head. The pedant. The one who will spend hours on various websites to ensure that a character is getting coffee in the right place. The one that demands a level of logic and consistency that makes my preference for writing spec fic seem rather masochistic. “You can’t use that,” the pedant said. “You don’t have Christianity.”
“Bloody hell,” I said.
“Nope!” it replied with irritating cheer. “Christian-derived, twice over.”
“Son of a bitch!”
“That one–” The pedant paused thoughtfully. “Huh. Actually, that one’s okay.”
Most profanity falls into two categories: obscenities such as fuck, shit, and piss, and blasphemies such as hell and damn. The former category tends to be seen as a stronger sort of swearing (although this is a somewhat new development in English). So basically, if I want my gruff mentor figure to express mild irritation, I have to work out his whole system of theology first. And did I mention that this is multicultural? Yup, that means I’ll have to figure out three distinct religions just so people can talk normally. This is why I drink, people.
Of course, all manner of slang, obscene or otherwise, is baked deeply in our culture and doesn’t always translate to other worlds. (Hell, idioms and slang can be problematic even in English.) Localized slang can be a great way to add depth to your world-building, letting us feel like these are real people in a place with real history and culture. I just tend to focus on the swears because I have a potty mouth, which often bleeds over into my characters.
And invented swears can be especially beneficial to the kidlit crowd, since there’s a certain breed of parent who gets the vapors and gets you pulled from the shelves over the slightest hint of salt in the dialogue. You’ve got everything from “stars” as a mild oath in The Lunar Chronicles, to “d’arvit” as a very much not mild oath in the Artemis Fowl books. Although this can be a fine line to walk; I personally gave up after 100 pages or so of The Maze Runner because I couldn’t take it anymore. In theory it was a good way to maintain a gritty feel without getting banhammered, but in practice they sounded like goddamn kindergartners. But that might have just been me.
As for the blasphemies, fantasy stories largely go the polytheist route, although funnily enough, it’s somewhat rare for this created religion to be referenced by any means other than swearing. Some even have the concept of hell and damnation, so hey, I could go that route and tell my inner pedant to piss off.
But the point is that I have to decide what route I’m going. The world around us is shaped by thousands of tiny details that have grown out of the collective experiences of millions who have come before, and in speculative fiction, those thousands of tiny details are all your responsibility. This can be equal parts exhilarating and terrifying. It will pop up when you least expect it, and can really throw you off your stride if you’re not prepared. But if you don’t address those concerns, it can throw your readers out of the story.
So listen to the inner pedant. The little fucker usually has a point.