If you're a fan of soaps as I was once, you'll understand this example.
Cody and Nevada are characters on As the Tears Fall. Suddenly, one day we learn that Nevada gave birth to Cody's baby 20 years before and put the child up for adoption without telling him. Nevada has been a regular since the show began, but until a 20-year-old blond bombshell showed up in town looking for her birth mom, viewers never had a clue about this secret in Nevada's past. Not only that, but when Cody joined the cast two years earlier, there was no indication that he and Nevada had ever been in a relationship let alone an intimate one.
The literary term for this is "foreshadowing." Soap opera writing lacks foreshadowing, in that it fails to lay the groundwork for what will occur later on in the story. In the real world, during all those years the soap was on the air, someone––Nevada's now geriatric mother or her sister or her best friend––would have known and probably mentioned something about the pregnancy. At the very least, when Cody came to town, Nevada would start acting strangely, like she had something to hide.
Soaps get away with this seat-of-the-pants style because it's hard to think up plot lines years in advance, but novels and short stories need to be more than just a series of unconnected shocking events. In order to keep us reading, the events need to be linked however tenuously. It's kind of the reverse of "Chekov's gun."In this case, if a gun is fired in Act II, it better have appeared in Act I.
There are many reasons why writers fall into soap opera writing. The most prevalent is simple laziness in not going back and doing the proper revisions. While some writers have the entire story in their heads before sitting down to write, and others outline, there's nothing wrong with making things up as you go along, or as some would prefer, letting your characters take the lead. The problem is, if you don't know in advance the path your characters will take, you won't be dropping bread crumbs along the trail.
If we wanted to turn As the Tears Fall into a novel or a good short story, as soon as the character of Cody was introduced the writer would drop hints of his prior relationship with Nevada and a secret she hasn't revealed. They don't need to be broad hints and for greater impact they shouldn't give too much away, but when the reader learns about their baby it shouldn't come totally out of the blue.
Another common reason writers don't foreshadow is a misunderstanding of how surprise endings should work. Back to our soap analogy, this is like Cody and Nevada getting married and sending their new found daughter off to college. After which, Nevada reveals that Kristina isn't really Cody's daughter after all, but the daughter of Dr. Gordon Rice whom she slept with while Cody was fighting in the Gulf War. (Another standard plot line soaps watchers will recognize.)
This is like the blindside surprises with which inexperienced writers often end their stories. They're working for "I didn't see that coming," when the reaction to a well-written surprise is "I should have seen that coming."Reread a classic surprise like Shirley Jackson's "The Lottery," and you'll find it's full of foreshadowing. The mastery is in the sleight of hand that leads the reader to misinterpret clues that should have been obvious.
Once the adrenaline rush of getting the whole story down on paper has dwindled, it's hard to force ourselves into revision mode. With short stories that oft repeated advice applies here more than ever. Let the piece rest until you can see it with new eyes. Since novels are written over a longer period of time, it can be a good idea to go back and revise as soon as you add something new to the plot line. If Cody suddenly enters the story in Chapter V, go back to Chapter I and place his yearbook photo in Nevada's dresser drawer.
That's the difference between writing for soaps and writing good fiction. Well, that and the money.