Gothic settings operate as monstrous characters alongside villains. [definitional]
Reflecting a pattern common to many Gothic horror tales, including Dracula, the nightmarish environment in this text functions as a character, another monster in the story. In Beckford's tale, the other two prominent monsters are Vathek and the Indian. Vathek's mother is also evil (remember, most Gothic horror texts have a malevolent woman), but she plays a secondary role in the story.
XREF: Connects to the Gothic tradition running from Dracula through contemporary horror, where environment is never merely a backdrop.
Sophia Rose Arjana, Muslims in the Western Imag…, loc. 506