“None of the young men were quite good enough for Miss Emily and such. We had long thought of them as a tableau; Miss Emily a slender figure in white in the background, her father a spraddled silhouette in the foreground, his back to her and clutching a horsewhip, the two of them framed by the back-flung front door.”

This helps in the development of the plot because it shows us why Emily has such dysfunctional relationships later on in life.

Also, the entire book is done out of chronological sequence, so the fact that the book goes from Present, to past, to present, could be considered a flash back. But the whole purpose of the story beind written that way is to help the reader get a better understanding of Emily Grierson.