Keeper of the Superfluous Es!

I can understand the way you feel about it. My reaction is pretty similar to what other people have said. I don't think you're overreacting if you have issues with the person. (it seems from what you've said that while you don't hate the person, he/she brings up some unpleasant issues/memories/whatever) I think you should contact the challenge moderator privately and explain the situation, saying that you'd rather not write for your requester, though you're still interested in participating in the fest no matter what. It's possible she's gotten emails from a couple of people who were unhappy with their requests and might want to swap. If she can't switch you around, then just write the fic you want to write for the request, ignoring who it's for. After all, she's not going to be the only person reading this and once you've started, you can try to sepereate the fic from the person who requested it. (after all, if you're the author, it's your fic, not hers)