Something I have personally wondered about a lot when contemplating how to write for Bloodborne, language-wise: what expletives do you imagine they would use in that universe? I've been reading through the various characters' dialogue from the game, and very few expressions are ever used that could count as such, the closest probably being "Dear gods...", and the negative, angry adjective "bloody" (as in, "bloody wench"). They don't have (or at least refer to) a "Hell" the way we do, and you don't ever hear them - no matter how uncultured - being vulgar; even Arianna, a professed prostitute, and the notoriously antagonistic skeptical man, seems pretty reluctant to be too direct.
I'd imagine that their expletives would revolve around the gods, blood and beasts. We could naturally completely circumvent this by simply not writing IC expletives explicitly, by paraphrasing it as "muttered a stream of expletives" and such, but I'm curious if you have any ideas.