A writer friend of mine blogged about coincidences recently, and it was something I hadn’t pondered before from a craft point of view. I think because it coincided (coincidentally) with my reading a few crime and mystery novels, I have a slightly different view than she does.
The usefulness of coincidence, to me, is genre specific.
Here are some examples of where you’d typically find a coincidence used to good effect:
Thriller – the protagonist escapes capture because he chances to see the bad guys or authorities arriving.
Mystery – the amateur sleuth stumbles on a clue that leads them in a whole new direction (the right direction) by being in the right place at the right time.
Romance – the lovers often meet by chance or are thrown together by circumstance.
Crime – the truth becomes clear in the intrepid police officer’s head because of a chance slip of the tongue, or a randomly told/overheard / seen bit of information.
Obviously this isn’t something that is always well done, and sometimes the coincidences stack up like a pile of fire wood until you really do want to set fire to the book.
If I were to write a rule about using coincidences, it would probably be “just one, and not at the end”, because a coincidence in the resolution is always just a bit tacky unless the main theme of the book is fate, luck etc.