Your novel’s ending must be inevitable, but preferably not predictable. Yeah, that’s easier said than done.
This is hard to plan for as you’re writing. Editing is the place to make it happen. Because once you’ve written the ending, it’s much easier to go back and layer in the plants that need to be present to make the payoff believable. That’s what makes a twist ending satisfying.
Too many writers aim for a twist and wind up playing tricks on their readers instead.
A twist takes what the reader already knows and shifts it. The best example of this is the movie The Sixth Sense (spoilers at that link) I’m not going to give the spoilers on that one here. Go read the plot summary, or better yet, watch it.
Murder on the Orient Express is another fantastic example. Since that story is 80 years old, I have no compunctions about spoiling it for you. In that story, Agatha Christie employs a mystery-novel convention—the collection of suspects all in one place. As Poirot investigates, the reader tries to figure out who the murderer is. The twist is that this time, it was all of them. As the reader, you have all the information necessary, but the ending still comes as a surprise.
A trick, on the other hand, introduces something the reader did not know or falsifies something they did. It can also result from characters behaving in an uncharacteristic way. If you hadn’t seen the guy get shot at the beginning of The Sixth Sense, the ending would be a trick. Or if Christie had withheld key evidence from the reader, that would be a trick.
Some have called the sudden conversion of an apparent good guy into a villain at the end of Frozen a trick ending. All that would be necessary to fix that would be to place a few hints early on that he’s not all he appears to be. His villainy isn’t the trick; it’s the lack of foreshadowing that makes it a trick.
What endings have left you feeling that the author was playing a trick on you? And when has a twist ending left you thrilled?