Few things can make a reader throw their book at the wall as quickly as a too-tidy and convenient resolution. When a novel ends with a deus ex machina or an implausible coincidence, it often feels like a betrayal of trust between the author and the reader. These devices may offer rapid solutions to plots we have trouble wrapping up, but they undermine both the quality and the story’s build-up of logic. I once ended a book with the protagonist just walking out the door. After three hundred pages of push-and-pull, she just walked out. If she had done that in the first 1200 words and I'd made it a short story, the reviews probably would have been better. Alas, I bungled it, big time.

A deus ex machina—translated as “god from the machine”—was born in ancient Greek theater, where divine figures were lowered onto the stage and fixed all the problems. I suspect this is part of why the conquest of ancient Greece occurred—everyone was waiting for the winged guy to drop down from the rafters. A well-known more contemporary example is H.G. Wells’ The War of the Worlds, where the Martians are defeated not by human ingenuity, but by Earth’s bacteria. First came the, “Wait....what?” Then I threw the book. That nobody-did-a-thing ending might be consistent with Wells' view of human fragility, but by crushing us with a resolution that removes agency from the characters, he made the unnamed protagonists’ fight irrelevant. I was 14. I paid for that book. Does he even realize how many cars I washed?

Readers who invest time following a character expect their choices and efforts to shape the outcome of the story—not external forces swooping in at the last moment. As readers, of course we accept coincidences that complicate the characters’ lives because they align with the unpredictability of real life. However, when coincidences resolve major conflicts or save the day, they come across as contrived. Probably because they are. An example of a good way to use a coincidence for a single moment within a story is in J.R.R. Tolkien’s The Hobbit, where Bilbo’s chance discovery of the One Ring isn't viewed as a shortcut. Tolkien mitigates the issue by tying the ring deeply into the mythology of Middle-earth, and the discovery is a stepping stone, not a resolution.

To avoid the deus ex machina pitfall, our characters need to hop over those hurdles with their own decisions, their own strengths, and their own ideas. Any other route requires some nicely placed hints early on that make surprising resolutions feel earned. If Wells had popped the protagonist into a science lab, a seemingly minor detail that could have happened in the opening chapters, he could have avoided making a bereft teenage girl cry. As I said, storytelling is built on a bond of trust between the writer and the reader. By crafting an ending that respects the character's evolution and basic logic, authors can deliver stories that stand the test of time, for all the right reasons.