As a writer (And avid reader) of alternate history novels, I’ve often been asked why I read this ‘what if’ genre. I think the best way to answer it is to simply say ‘Have you ever wondered ‘what if?’
What if I was a police officer, or a medic, or a doctor, instead of a teacher? What would be changed? Who would have my job? Whose world would be turned upside down, for better or worse? Who would I have met/not met? How many of us ever wonder how the world would be different if one little thing happened? This is a ‘turning point’ or life change, or ‘point of divergence’ as some people say.

So what makes a good turning point?

I put forward three rules for good turning points.

1. It must be believable (makes sense in the story context).

2. It must be reasonable (COULD actually happen based on technology, characters, etc)

3. The results must be possible based on the outcome of the event.

Let me give you a good example. In my story, Brass Legionnaire, I have two main points of divergence. The first is the rescue of Julius Caesar by Brutus. The change is that Brutus loved Caesar (True in real life) so much that he was willing to forgive the general’s ambitions to save his life, rather than kill him for the sake of the republic.

Believable? Yes, I think so (so do several professors I’ve talked to over the years, remember, it was a big surprise to Caesar at seeing Brutus among his assassins)

Reasonable? Yes, hasn’t love for friends, family, or significant other driven you to do something a tad bit crazy? This is just asking Brutus to put his friend above the needs of the republic, a stretched, but still reasonable, idea.

Outcomes: Well, the assassins get turned in, Caesar gets his Emperorship, and the Empire gets off to a roaring start, rather than suffering through a few years of civil war at the hands of Augustus (Octavian) and the rebels. With security and stability, plus respected and talented military and economic leadership, the foundation for our world has been set.

So what is my point? Great authors create realistic and possible worlds by making their turning points believable and possible. Some of my favorites are Harry Turtledove and S.M. Stirling. Mr. Turtledove, in particular, creates beautiful portrayals of worlds that have undergone one major change, but it throws off the entire course of history. See ‘Opening Atlantis’ for a great example.
Let me know what you think!