Lord Ruthven is the story’s titular vampire and antagonist. He appears in the midst of London society one winter and strikes people with his “dead grey eye” (27) and “deadly hue” (28). Polidori uses connotation and repetition to foreshadow the monster underneath Ruthven’s magnetic demeanor. He is impervious to the seductions of women known for their adulterousness and partial to those known for their domestic virtues.

Over the course of his travels with Aubrey, Ruthven gradually reveals his sinister character. Ruthven’s most dangerous personality trait is his charisma, which he uses to manipulate and exploit gamblers, women, and Aubrey. Under the guise of benevolence, he bestows charity upon those he judges as profligate to sink them further in their vices. During their travels, Ruthven seeks out such people at every stop. Watching Ruthven gamble against his victims, Aubrey describes him as a “cat […] dallying with the half-dead mouse,” continuing Polidori’s trend of using language that connotes predators and death to describe Ruthven’s demeanor (35).

Women fare just as badly as gamblers under his influence; The “deformity of their vices” is “unmasked” by their encounters with Ruthven (37).