Thanks for this link Frank-- I was so excited to discover Mark Twain. A particularly interesting thing about the edition of Pudd'nhead Wilson I have is that includes an afterword by Twain, explaining the process that led him to write the book-- he had actually started off writing a completely different story (about a pair of Siamese twins) but got distracted by the minor characters, who turned out to be more interesting and, after several months of trying to decide what was wrong with his draft manuscript, he decided to turn it on it's head. The twins were split up and relegated bit parts. Fascinating stuff.
Yes, that is most interesting, Sian. It reminds me a bit of when Debi Alper was saying that she doesn't know where her characters are going. She started writing for women's magazines to make some money, but because the characters always went off and did "unsuitable" things unbeknownst to her, she couldn't use the material for that purpose. Hence the novel!