Chillingworth is the epitome of a devil's pawn. One hardly knows whether to call him human; no natural person can transform himself from a respected, compassionate citizen into an evil, mysterious character as quickly as Roger Chillingworth is transfigured. Roger Chillingworth proves himself "unnatural" and "devilish" on many occasions.
Roger Chillingworth is first introduced in the scaffold scene. The approach Hawthorne takes to enlighten the reader about Chillingworth's appearance fits the savage nature that the reader experiences later in the novel. Roger Chillingworth is described as suddenly appearing, perhaps dropping out of the sky. His association with physical deformity, savages, and power, in the beginning of the novel, begins to make us aware that his character is not going to be a pleasant one. Perhaps it is this first look at his character that relays a sudden evil tone, a tone Nathaniel Hawthorne is known to elaborate on in each of his pieces of work.
As Roger Chillingworth begins to be consumed with vengeance, he becomes less of a character and more of a symbol for hatred and devilry.
Hester's presence with the child on the scaffold causes Roger to question the townspeople about the previous year's events. When Chillingworth learns that Hester has commit adultery, he turns to revenge. Nathaniel Hawthorne describes Roger Chillingworth's reaction to the news as a sudden physiognomy change - a snake suddenly gliding over Roger's expression (Nathaniel Hawthorne, The Scarlet Letter. New York: Oxford University Press, 1962. page 62); the relationship between Roger and the serpent is used by Hawthorne to relay to the reader an underlying evil in Roger Chillingworth.
Indeed, Hester Prynne's sin acts as a stimulant to transform Roger from the honest, studious physician he is when they get married, to an old man bent on revenging his wife's...