One of the things that I love about some of the stories I've read in the past, is the sudden surprise of the plot taking a completely unpredictable turn. Whether it be for the worst or the best, these twists and turns in a storyline can really make for an exciting read. It's something that I try to put in my own stories as well when I can manage it.
But, while the idea of surprises in a story are fun to think about...they can be very diffiult to pull off sometimes. First of all, the said 'twist' can't just come completely out of left field, or it might come off as confusing. There has to be some kind of set up that leads the reader to a certain point where you can 'pull the rug' from under them. However...the set up has to be subtle enough to make the pay off somewhat unexpected. Otherwise, most readers will see it coming a mile away.
This week's question is, how does an author go about creating an unpredictable storyline? Even without the big shocks or giant twists, how can someone write a 'boy meets boy' story without it following the same formula as the billions of stories that came before it? And, if you can, give us an example of an unpredictable plot point that you truly enjoyed. (Online stories, books, movies, tv series, whatever.)