I remember a fanfic that focused on Karen (and I think it was a Karen/David Michael fic...), and if I'm remembering correctly, Karen and Hannie had had a fight sometime in middle school. I can't remember much of it, but I think Hannie got sick of Karen pushing them around. Nancy, I imagine, found herself in the middle and eventually found some theatre kids and stuck to them. I've always felt this would have been the most likely outcome, especially as I've been re-reading the BSC:LS books lately. I also picture Karen being the kid the rest of her classmates tolerate, but just barely. The one who is, for the most part, well meaning, but still comes off as bossy and the kids therefore avoid her because of it.
What do you folks think?