First of All
So, knocking a few things out of the way- I do enjoy the OSR/GLOG community, and I am an avid fan of Arnold K. (https://goblinpunch.blogspot.com/), however, this blog shouldn't, I wouldn't think, be considered a part of that crowd. Mainly because I have a much larger, non-roleplay focused scope for this blog. Will i write about roleplaying? Of course. But I intend to write about much more in the scope of worldbuilding. And that's really what this is all about here, worldbuilding and to a lesser extent, writing. It's been a joy of mine for as long as I can remember, so it's apropos that i construct a digital soapbox with which to promote my weird ideas.
Moving on, quickly.
The Common Tongue
Common. Everyone speaks it. And I mean everyone. Villagers? Common. Party members? Common. That one goblin you managed to capture and tie up? "He spits vile insults at you in broken Common." See? Now why is this? There's an extremely simple answer. It's convenient. And that's not an insult! Imagine the irritation if your party could not advance the plot due to language barriers? How... horridly realistic. There is a certain level of realism in roleplay, or even writing that just stinks. Plainly stinks. No one wants to roleplay how you got dysentery because you haven't been washing your camp soup pot.
Except, that is not wholly true; given the right players and the right atmosphere, that might be just the ticket. Realism, or more accurately, acknowledging consequences you typically ignore, can be powerful, fun, and engaging. It's this sort of realism drip-feed I'd like to engage with.
Language is... complicated. Trust me, I was getting a BA in linguistics at one point. There's no way you can capture the whole mess in a well played game of dnd. But needless to say, we've tried. To some, "common" is shorthand for "the language of this nation we happen to be in" within the fiction of the session. For others, Common is a lingua franca, a language of trade and the in-between of nations and peoples. Personally, I feel there's more to chew on with the latter. Even so, this latter option tends to be depicted wholly without regard to reality. Even with this explanation, we tend to fall into the same trap of "everyone speaks Common."
"Lingua Franca" is an interesting term. Historically, it referred to an actual language, spoken in the Levant by sailors, traders, soldiers, and others. It was what linguists call a "pidgin" (rhymes with pidgeon), which is, to put it horridly simply, the sort of "Me Tarzan, you Jane" language tool that arises when those who share no language need to communicate. All kinds of circumstances can give rise to these little linguistic Frankenstein's monsters. Trade comes to mind, but migration, slavery, groups of people moving in together; these are all excellent cradles for a pidgin language. Now, as Wikipedia, the God of Knowledge (and crowdsourcing) would have you know, "Fundamentally, a pidgin is a simplified means of linguistic communication, as it is constructed impromptu, or by convention, between individuals or groups of people. A pidgin is not the native language of any speech community, but is instead learned as a second language." Let us go forth with this nugget or real life lore, and worldbuild.
"Common" is a pidgin. It was born a long time ago, baptized in the fire of a crusade. The Piçdmo, as they were now calling themselves, had pushed into the very edges of the Eastern Mountains, an old and worn range, filled with small communities of many peoples. You see, these Mountain Folk had within their lands, a number of truly ancient structures the Piçdmo felt were sacred to their religion. Some decisive battles and a few shady deals later, and the Piçdmo found themselves in control of a nice new slice of territory. Commence the praying. However, there was a problem. These rowdy hillfolk did not speak Piçdmoti! The pilgrims and the mountain peasants had instead taken to debasing their tongues into a truly crude form, blasphemous in it's poor enunciation, so poor in grammar as to make the great poets weep. Needless to say, the smallfolk kept on communicating as they mingled and shared in one another's company.
Enter the Dirth. Traders from beneath the earth, they brought the same goods they had always brought to these lands in times of peace. Gems, metals, quality steel, and other such useful baubles. They too, engaged in the rearing of this bouncing baby pidgin, and soon, Kapa Ki began to spread.
Kapa Ki, or Common, is not precisely a language in the way English or German is. It's a sort of linguistic tool, a way to communicate simple messages. Traders, travelers, immigrants, it is useful to all sorts of folks. When one must be heard, they are heard in Kapa Ki. It is thus that Kapa Ki has few sounds, so one of any tongue could pronounce it. And it is thus that Kapa Ki has few rules of grammar. No need for intense precision when context and a firm handshake will do the trick. Sealing the deal doesn't always require high prose, and so Kapa Ki is an effective, but blunt instrument.
The players can make great use of this- if they, being traveling ne'er do wells with a craving for money and an unscrupulous greed want, take advantage of the fact that many of their dealers, brokers, and guildmasters don't know their native tongues. Perhaps the GM could just as easily throw it back in their faces. It's a useful tool, being able to limit the flow of information. It won't fit for every campaign (after all, we gotta have those darned broken-common speaking goblins to insult us), but it might be just the spice you were looking for.