Final answer:
A possible sequel to the story of Rainsford's victory could explore his psychological struggle, a potential vengeance-driven Ivan, and Mr. Whitney's search efforts. The island setting continues to be central, as Rainsford reconciles his experiences with his moral compass, possibly reflecting on the conflict between civilization and savagery.
Step-by-step explanation:
After Rainsford's victory over General Zaroff, one could imagine a sequel in which the very essence of the hunter and the hunted is further explored. If Ivan survived, perhaps he becomes a new antagonist, driven by vengeance and an even deeper brutality now that Zaroff is no more. It's plausible that Mr. Whitney, noting Rainsford's mysterious disappearance, mounts a search, leading to a rescue or an unexpected entanglement in the island's grim pastimes.
Rainsford's psychological struggle with the events he endured would likely be a central theme, potentially pushing him towards a confrontation with his own morality and humanity. The climactic moment of his triumph sets the stage for these subsequent conflicts, while the island, still remote and menacing, continues to serve as a pivotal setting for the unfolding narrative. Through his ordeals, Rainsford may have developed an intrinsic understanding of Zaroff's perspective, teetering on the edge of becoming what he despised, unless he reaffirms his values.
Utilizing the textual evidence from the original story and inferring the character development and thematic evolution, the sequel can build upon and reflect back on the inherent conflict between civilization and savagery, a battle not only in the outside world but within the psyche of our protagonist.