I'm about to start writing the eighth book in the Grk series and my thoughts have turned to the Reichenbach Falls.
The Reichenbach Falls drop a hundred metres down a Swiss slope. On 4 May 1891, this is where Sherlock Holmes fought his arch enemy Professor Moriaty. Both of them fell to their deaths in the water. And that was the end of the world's most famous detective.
Except it wasn't. On his way down, Holmes managed to grab a tuft of grass and pulled himself back to safety. Or so Conan Doyle wrote a decade later when his public demanded that he bring Holmes back from the abyss.
Conan Doyle killed Sherlock Holmes - or tried to kill him, anyway - because he was exhausted by his own fictional creation. He couldn't imagine how to continue writing about him. So he threw him over a Swiss waterfall.
I'm not going to do that to Tim and Grk, the heroes of my series that started five years ago with A Dog Called Grk. But, as I always do before I start a new book about them, I wonder how I can make this one different enough to be interesting.
Each of the Grk books is self-contained; you don't need to have read the first in order to read the fourth or the seventh.
Like Sherlock Holmes - or Just William or Jack Reacher or James Bond or hundreds of other fictional characters who appear in a series of novels - Tim and Grk hardly develop from one book to another.
And so the series could continue for ever.
In theory, I could write 192 of them. (Each of the books is set in a different country and there are currently 192 countries in the United Nations.) That is, if I could find enough ways to make them interesting to readers - and, more importantly, to myself.
I'd be intrigued to know how other people reinvigorate their long-running characters - and if they've ever been tempted to toss them over the Reichenbach Falls.