Plot twists may seem easy, but they are in fact not. You have to balance the “this was totally unexpected” with “this makes sense”. It has to make sense logically and it has to be “twisty” enough to surprise the reader. You need to have a little more than just a stunning betrayal. There need to be good reasons for the betrayal.
Plus, the element of foreshadowing is paramount. You have to be careful not to employ to much of it, and you have to make sure not to put too little of it in. The line between “sufficiently foreshadowed”, “insufficiently foreshadowed” and “overforeshadowed” is relative, so this betrayal will make more sense to some readers while others will be completely lost.
Not to worry, though. Even though plot twists can be challenging, they can be greatly simplified through the use of a step-by-step process. Remember, the goal here is balance.
You’ve heard me write about foreshadowing before, but there is no time when it’s more important than when you are planning a big plot twist. Try to make the foreshadowing natural. Make it as if this character were earnestly trying to hide their true colors, but let the façade slip at one time or another.
To do this, add a few coincidences that will allow the reader to build up a mild suspicion. A plot twist is always a larger revelation, so make smaller revelations throughout the story. And don’t reveal a large part of a smaller machination; reveal a small part of the larger machination.
You want there to be no question in your readers’ minds: there is definitely something going on here, but it is unclear what that something is. You can reveal a bunch of little things, but only if they will play a part in revealing the “one big mess”, It’s always better to stick with a big, mind-blowing revelation over a bunch of small ones.
Once you’ve got the foreshadowing element in place you can now move on to the actual twist. Now, don’t trust to your writer’s instinct here: don’t walk in with a feeling of “oh, I’ll just decide on the fly who’s going to betray who”. Plan in advance. Before you write the actual twist, decide who, what, when, and where the plot twist will take place.
This is the most important step. Without careful planning, you may very well choose the “twistiest” option that will delight you but confuse your readers. Above all, choose the twist that is the most unexpected while making the most sense. Don’t pick a twist that everyone was expecting but makes sense, and vice versa.
When it comes time to make the actual twist, do exactly as you planned. You can go back and edit it later, but at least the bare bones need to be there. Don’t allow yourself to wander, and reveal the whole mess with no additions. Stay focused.
Then, you have to deal with the aftermath of the twist. Whether it’s a betrayal or a revelation of a secret plot against king what’s-his-face, there’s going to be trauma. Don’t forget this part. There will be people who are appropriately shocked and/or angry, perhaps including your reader. Accommodate feelings of this kind accordingly.
If I were to sum up this article in two rules: Foreshadow often and vaguely, and always make it make sense in some way, shape or form. If you have these two elements, any kind of plot twist will be easy for you.
Good luck, and happy writing!