Twisting the TalebyCal Y. Pygia©
To write an erotic short story with a surprise ending, create a situation that involves a conflict between the main character and a rival or adversary. These characters should struggle against one another to reach the same goal or opposite goals for different reasons (motives). Be sure to set up a series of increasingly difficult obstacles for your main character to overcome as he or she seeks to achieve his or her goal. At first, have things either going his or her way or going against him or her. Then, have the story end in the opposite way, with things turning out for the better or the worse, depending on whether they were initially going poorly or well, respectively. In addition, end your story with a surprise.
Here is an example, based on "The Calendar," one of my own short stories.
At the beginning of the story, several customers urge their barber to enliven their visits to his shop by hanging a pinup calendar on the wall for them to admire while he cuts their hair, arguing that it will be good for business.
The next time one of the regular customers visit's the shop, it is crowded with clients of questionable gender. When this customer's turn comes to have his haircut, he asks the barber why his shop is crowded with "faggots."
The barber answers the customer's question by referring him to the new erotic calendar that hangs on the wall, which features nude men cavorting with one another. When the customer demands to know why the barber has hung a gay calendar in his shop, the barber replies that he himself is gay, adding that his customer was right: having hung an erotic calendar on the wall has improved business.
Part of the trick, as it were, in writing this story was o depict the regular customers as not only heterosexual but also as macho men and to ignore the barber's sexuality altogether, with the result that the reader assumes that he is also straight. This way, when he reveals himself to be gay, the reader is surprised. The same technique is used in any other story to effect a surprise ending: set up one expectation for the reader and then have the story end in a different, but nevertheless plausible, way.
Here is another example, based on "Photo Op," another of my stories.
A man driving from Kansas to Las Vegas, Nevada, waits his turn to refuel at a gas station, ogling a beautiful young woman in a mini-skirt. It's a blustery day, and he hopes a gust of wind might lift her skirt so he can get a glimpse of her panties.
As the wind teasingly flutters her skirt about her thighs, the man muses upon the thought of her underwear, wondering about the style, cut, fabric, and color of her panties and wishing he had not packed his camera away in the trunk of his car.
Finally, a gust of wind does lift her skirt above her waist, and the shocked motorist sees male genitals in place of the panties he'd expected to see. Again, he is sorry to have packed away his camera, lamenting the spectacular "photo op" he has missed as a result.
The trick, so to speak, in writing this story was to focus the reader's attention on the femininity of the transsexual character and, more specifically, on the main character's obsessive interest in what type of panties she might be wearing. By continually focusing on the panties' style, cut, fabric, and color, the expectation that she is wearing panties is created and maintained for the reader. Therefore, when it turns out that she is not wearing panties--and that, moreover, she is a transsexual rather than the biological woman that the main character has assumed she is--the reader is surprised. Again, the writer has set up one expectation and ended the story in a different, but plausible, manner than the one that he made his reader expect.
Let me offer one more example, again from my own work. In "Nothing All," a woman in a BSDM relationship is anxious because she doesn't know why she is going to be caned and she relies upon knowing the nature of her offenses against her master as a means of avoiding the instrument of discipline by avoiding repetitions of her misdeeds. She tries to imagine what she may have done, or not done, or done wrong, but she can think of nothing, and she becomes more and more alarmed before and during her savage whipping. Finally, once the brutal punishment is over, she knows that her master will allow her to know the reason for his having caned her; therefore, in the future, she can avoid displeasing him in this way and avoid further punishment for the same offense. Throughout the story, the reader has shared her expectation that her master will identify the reason for the caning, and, therefore, he or she is surprised when the victimizer replies to his victim's earnest query as to what she has done to have deserved such a merciless beating, "Nothing at all." (By the way, I have also written a gay version of this story, which also appears on Literorica.com).
In general, a surprise ending works because the writer exploit's the continuum between the two extremes that characterize most thought and understanding. Seldom is anything pertaining to human thought, belief, emotion, or conduct black or white; it is almost invariably some shade of gray. Hence, in relation to human behavior, particularly in the indulgence of the senses, Aristotle urged "moderation in all things." By moving the reader in the direction of one extreme, or opposite, such as, for example, naiveté, the writer ends by showing the reader that the character whom he or she has assumed to be naïve is, in reality, sophisticated or experienced. When the writer accomplishes his duplicity adroitly, as by O. Henry, for example, or H. H. Munro, or, hopefully, yours truly, the reader is surprised.