I found this on a Joan of Arcadia fan site--the one where MShaffer has his stories. It's another Season 3 of Joan, and it looks lengthy and well-written:
http://www.fanfiction.net/u/963303/CharlesTheBold
This should satisfy my Joan palate for a while! Before I get to that, though, I want to read MShaffer's newest story, The Child, Part 2.