Here's why:
* Emily Grierson's isolation and decline: She is presented as a woman trapped in the past, refusing to acknowledge the changing times and clinging to a romanticized image of her lost love, Homer Barron. Her social isolation and the decaying state of her house reflect a sense of decay and the decline of the old South.
* The secrets and hidden darkness: The story revolves around Emily's secrets, particularly the murder of Homer Barron. This hidden darkness within her reflects the dark underbelly of the genteel Southern facade.
* The grotesque and macabre: The discovery of Homer's body, preserved in Emily's bed, is a graphic and unsettling image that is central to the story's gothic atmosphere.
While other archetypes like the southern gentleman (Homer Barron) or the ghostly figure (Emily herself) are also present, the fallen woman archetype is most prominent in "A Rose for Emily" because it encapsulates the key themes of decay, decline, and the hidden darkness of the South that characterize Southern Gothic literature.