In Faulkner's "A Rose for Emily" and Jackson's "The Lottery," your introduction wants to present to the reader the importance of devices used by each author to grab the reader in the last moments of the tale, pulling the proverbial "rug" out from under one's mental feet, and catching the reader completely by surprise. It should also include the fact that the devices used in each story are common, yet very different—and the stories are also dissimilar, however, each author is able to achieve the same effect. (This shows how complex and malleable English is.)
We know that Faulkner keeps the reader off base by jumping around and switching up the story's timeline or chronology. This keeps the reader from too easily sensing a pattern.
Jackson uses the hidden meanings behind symbolism to achieve the same effect. She also creates a positive setting that lures the reader into a false sense of normalcy and calm. In both stories, the author artfully manipulates the reader to arrive where she wants him/her to be, and then throws away these preconceived notions and brings forth the madness and chaos. It is a very similar process.
The time shift can be seen between parts one and two:
"See Colonel Sartoris." (Colonel Sartoris had been dead almost ten years.) "I have no taxes in Jefferson..."
So she vanquished them, horse and foot, just as she had vanquished their father's thirty years before about the smell.
Between these two sections, thirty years is skirted—the book takes the reader into the past. Losing track, the unnamed narrator can easily lose focus (as does the reader) so that when the ending is presented, it is a complete surprise.
In Jackson's tale, the setting is greatly influential in throwing the reader of the scent of the shocking end to come. After school is out for the summer, on this day of the gathering, Jackson describes the kids—and the almost cliché-like afternoon:
[The children] tended to gather together quietly for a while before they broke into boisterous play, and their talk was still of the classroom and the teacher, of books and reprimands.
Both of the techniques of Faulkner and Jackson are equally effective and highly dramatic—even though they are, paradoxically, presented very quietly. The truth remains a well-kept secret until the very end of the story.
This is an example of an introductory paragraph I might write with your topic in mind:
Authors are generally adept at plot development by engaging the use of countless literary devices to allow them to create stories that are not only interesting and exciting, but unique as well. In William Faulkner's "A Rose for Emily" and Shirley Jackson's "The Lottery," the writers use common devices to describe the characters and create the perfect settings for their stories. While each uses a different device (Faulkner uses "flashback" and Jackson uses "foreshadowing"), and each story is especially distinctive, their ability to use these devices with such skill has the same result: eerie tales—with endings no one ever sees coming!