By now, it must seem that I am easily annoyed, and that may be the case. That being said, here is another of my pet peeves: deus ex machina. Deus ex machina is a plot device where the author seems to get the main protagonist into such a pickle that they basically have to make a “God call”, introduce something that wasn’t there before, and tie everything up into a nice little bow.
My favorite example of this plot device actually came from a TV series that ran for almost 10 years. There were three lovely sisters who had special powers and spent most of their time fighting demons. This is a great plot. If you add dynamic characters, and a bit of drama, to a terrific setup. The problem with the show was in the execution. The protagonists and antagonists were introduced at the beginning, as was the problem, which, again, was a great setup. Then there was drama for the majority of the hour long program and at the end, one of the three protagonists would throw a potion at the antagonist and he or she would disappear. If it was that easy, the protagonists should have done that at the beginning and saved an hour of drama that had nothing really to do with the problem presented at the beginning.
There are plenty of examples of this type of plot device, but it should not be used. I repeat, it should not be used. A good setup and a good idea of where your story is going will prevent a God call from happening. If, by some chance, you write whatever comes to mind and correct later, be sure to add something at the beginning or even toward the middle that will tie into the solution at the end, and keep your readers from round filing your story.