Use of "Yeah": Yay or Nay?

[Nimue]

Yes. The anachronism is there for a purpose. Members of the more established native cultures of the setting tend to use more formal, archaic speech, while the newcomers' speech patterns are more modern and casual. I did this because I wanted an obvious distinction between the two--highlighting their opposing cultures and mindsets.

For younger characters of the native cultures, I decided to blend archaic and modern to illustrate how, despite attempts to stop it, the different cultures inevitably will influence each other and bleed together.

Miekkhal's speech patterns are a big part of his characterization, too. For the first part of the story he conforms to the formal speech of the culture he's been assimilated into. Later, when he starts to identify with his birth culture again, he adopts its more modern speech. I kind of want it to be a jarring change at first, to really underline his cultural about-face (it's supposed to come as a surprise to both Tomrin and the reader).

From this, it sounds like you have very good reason for that "yeah"! I'd have no issue with it in this context whatsoever. Goes to show how context is king with word use--there are no good or bad words.

However, I'm going to make a point that I feel I've made a few times before. The argument against using modern slang in fantasy is not really one of strict historical accuracy or grammatical prescriptivism. It's about reader expectations. If you chuck a few slang words into an otherwise by-the-book serious adult high fantasy novel, the average reader is going to think that this is poorly-written dialogue.

You're free to have your characters say whatever you like, but you need to make the reader believe that they would say that, in this world, in this scene. Otherwise, it's going to cut suspension of disbelief right in half.

 

[Tom]

Thanks for the advice, everyone! I'm out of thanks bullets, unfortunately, and it feels kind of weird not to be able to acknowledge your great posts.

 

[Russ]

I have no problem with the "yeah" used in this context.

A lot of how readers perceive speech patterns like this is based on their own experience, as noted above.

If I heard someone using "yeah" the way it was used here it would remind me of the pattern of speech of many of the Rhodesian/Zimbabwean/English South Africans who I knew when I was growing up.

If you used the "eh" suggested by an earlier poster I would think Canadian for sure eh.

 

[Penpilot]

How about "yah"? Much depends on context, of course, but if you have introduced "yah" earlier, or even some made-up word (single-syllable and short), then it would work fine. "Yeah" sounds modern to my ear.

A lot of how readers perceive speech patterns like this is based on their own experience, as noted above.

For me, Skip, the video below is what came to mind when you suggested Yah.