Why do readers crave continuing series where characters appear over and over again? (This is a question that pops up a whole lot over at my own blog, since it applies rather heavily to the mystery field.) The Telegraph's Helen Brown investigates this phenomenon on the heels of Michel Faber's just-published short story featuring Sugar, the character of his bestselling THE CRIMSON PETAL AND THE WHITE. In his introduction to the collection, Faber quotes from the cardboard box full of letters he received from readers of The Crimson Petal. So many people wanted to know where Sugar and her young charge Sophie went: "Australia? New Zealand? Back up North? Please - if you know - give us an idea. We worry about Sophie!!"

So what's going on here? Noted SF writer Michael Moorcock explains his own rationale for writing series characters is based on what he read as a child. "I loved [JUST WILLIAM] because I identified thoroughly with him. He was given to asking adults sticky questions, and few red-blooded kids could fail to love him. In a sense, Wodehouse's characters were the same - rather bewildered by the cruel world, as it were. John Carter came a bit later. With him, it wasn't so much the character as the landscapes." Ah yes, the creation of worlds where characters can pop in and out - that's a popular idea, too.

Series is associated with genre fiction but look how many literary writers - John Updike, David Mitchell, Julian Barnes & Anthony Trollope did recurring characters or series. And then there are the metafiction types, like Jasper Fforde having his way with the classics in his Thursday Next & Nursery Crimes series. But perhaps the most enduring mysteries are those offered up by readers themselves. "I wish I knew what became of some of the readers who took the trouble to write to me. The man who had cancer and read The Crimson Petal in hospital: is he still alive? The prostitute who said she was leaving the game and returning to education: did she? But I will probably never know."