How does Stevenson deviate from realism in "The Beach of Falesá"? What are the gothic aspects he uses for this shift?
"The Beach of Falesá" is one of R. L. Stevenson's more naturalistic works, set in the present day and without the swashbuckling adventure of Kidnapped or the path-breaking science fiction of the The Strange Case of Dr. Jekyll and Mr. Hyde. It's a straightforward story about deception and vindication, but with an underlying message about the difficulties inherent in cross-cultural relations between Europeans and Pacific Islanders and, at least implicitly, about the injustice of imperialism.
The novella is gothic only in the sense that the island people are imposed upon by a man named Case who has tricked them into believing that he has supernatural powers or that he is, or controls, a "devil" whom they call Tiapolo. Case is a trader who is the rival of the narrator Wiltshire, and he has turned the "natives" against Wiltshire by convincing them that the girl Wiltshire has married has had a taboo placed upon her.
Case's power stems from his having set up a series of auditory and visual tricks deep in the island forest. A "Tyrolean harp" creates eerie sounds when the wind blows through it, and statues covered in "luminous paint" have been placed in a kind of demonic jungle shrine to frighten the islanders, who are stereotypically portrayed as ignorant and gullible. It is a veneer of the gothic and preternatural Stevenson presents in the tale, and in the end, Wiltshire succeeds in blowing up Case's "temple" and killing this manipulator, though at the cost of Wiltshire's breaking his own leg and having to start anew as a trader in a different location.
What could be labeled gothic, at least metaphorically, however, is the frightening ability of a man such as Case to perpetrate such a deception. In some ways Stevenson can be seen to have anticipated Conrad's Heart of Darkness. Like Kurtz in Conrad's novella, Case has set himself up as a kind of god over the "natives." In both cases it is an especially perverse form of colonialist dominance being carried out by an unscrupulous and borderline psychotic individual. Whether or not these kinds of ruses were successful in reality, there is surely something gothic in the very idea of them as attempts to use superstition and vulnerability to bolster the power dynamic that existed between colonizer and colonized.
In Stevenson's treatment, Wiltshire, though his speech and attitude are racist, can be seen as subverting this dynamic, by legitimizing his marriage to Uma and by destroying Case's phony religious impositions upon the island people. "The Beach of Falesá" is thus a seminal progressive work, though it makes its points in a roundabout way and unfortunately expresses or seems to uphold the negative stereotypes so commonly held at the time by Europeans about nonwhite peoples.