Phonology and sound inventories are considered the most important criteria when talking about language change so that's why I'm focusing on that, but really it's combination of pronunciation and grammar, then with vocab being like the least important thing because of how volatile it is (think slang) but can still make a difference if there's enough permanent ones (think regionalisms).
To massively simplify, imagine language change is a color scale from red to purple to blue, where each generation is a little less red and a little more blue. A person who speaks red language (say Old English for example) would have kids who speak red with just a speck of blue. The parents wouldn't adopt that speck of blue though, everyone understands them and that's just kids these days rabble rabble! Then those kids have kids who speak red with two specks of blue, and so on and so forth. If we look at one language over its lifetime we might say pure red is Old English, pure purple is Middle English, and pure blue is Modern English (with blue-violet being Shakespeare) but how to classify the gradients and how to say when exactly one language became the other is something linguists fight about all the time.
As you say the natural thing is to not change your own speech (beyond slang usually, within one dialect anyway) just because there's a new generation, everyone around you can understand you after all!! But with an immortal being like the nations, the question is at what point in the gradient do they give in and learn the change? And is it like learning slang or do they hold out so long it's like learning a new language? To what degree do they remember the old versions the further they get away from them?
I handwave canon with nation language just so I can think more in-depth about them with human limits but obviously that's because I love this shit lmao
BUT YES I'M OF TWO MINDS ABOUT IT TOO I love the fact that all Ludwigs I've ever played with figure out who Julchen is by 'dat German' and I like Teuton being lost about all the things, but on the other hand I always assume they can talk to Germania fine oops. this keeps me up so often you don't even know sob
Re: ooc
To massively simplify, imagine language change is a color scale from red to purple to blue, where each generation is a little less red and a little more blue. A person who speaks red language (say Old English for example) would have kids who speak red with just a speck of blue. The parents wouldn't adopt that speck of blue though, everyone understands them and that's just kids these days rabble rabble! Then those kids have kids who speak red with two specks of blue, and so on and so forth. If we look at one language over its lifetime we might say pure red is Old English, pure purple is Middle English, and pure blue is Modern English (with blue-violet being Shakespeare) but how to classify the gradients and how to say when exactly one language became the other is something linguists fight about all the time.
As you say the natural thing is to not change your own speech (beyond slang usually, within one dialect anyway) just because there's a new generation, everyone around you can understand you after all!! But with an immortal being like the nations, the question is at what point in the gradient do they give in and learn the change? And is it like learning slang or do they hold out so long it's like learning a new language? To what degree do they remember the old versions the further they get away from them?
I handwave canon with nation language just so I can think more in-depth about them with human limits but obviously that's because I love this shit lmao
BUT YES I'M OF TWO MINDS ABOUT IT TOO I love the fact that all Ludwigs I've ever played with figure out who Julchen is by 'dat German' and I like Teuton being lost about all the things, but on the other hand I always assume they can talk to Germania fine oops. this keeps me up so often you don't even know sob