I'm doing that irritating thing of skipping the main point of your post in order to comment on something you mention to explain that main point. Sorry.

But it made me wonder if you were reading Manda Scott's Boudica series? There's a character in it who I think would meet your specification (and I won't say which one, in case you haven't read it, and can be persuaded to). And she writes much better than J.K. Rowling...