Let us say, simply for the sake of argument, that one might be writing a short Dresden Files story from Murphy's POV, in the third person. Which would be a more natural-sounding name to call her, "Karrin" or "Murphy"? I started out with "Murphy" because it's how I think of her, then decided that most people probably don't think of themselves by their surname and went through and replaced it all with "Karrin", but now it reads a bit odd to me since the books always call her by her surname. Thoughts?
ETA: After trying it both ways, I think I'm going with Karrin because that's what sounds right for the story and for the level of third-person that I'm going for here. Thank you for the input, everyone; I'll be back to answer comments but right now I'm rushing off for work! :)