While serving as Dimmesdale's "leech" (a term for a doctor) Chillingworth begins to suspect that Dimmesdale's condition may stem from stress caused by some kind of secret. He tries to find out this secret, but Dimmesdale refuses to divulge it.
Chillingworth recognizes the effect of secret sins. Yet he hides things too, and becomes an actual "leech" feeding off Dimmesdale's sin.
One day, Chillingworth and Dimmesdale notice Hester and Pearl in the cemetery outside Dimmesdale's home. Pearl is playing on the headstones and attaching burrs to Hester's scarlet letter.
Pearl's connection to the occult is here linked to her fixation on the scarlet letter. This fixation results from Hester's secrecy.
Pearl throws one of the burrs she is carrying toward Dimmesdale. She tells Hester that they should leave since the Black Man has possessed Dimmesdale and will get them too.
Identifying Dimmesdale as a sinner, Pearl throws him an extension of the scarlet letter. But is his sin adultery or silence?
Dimmesdale's health gets worse. Chillingworth attributes his illness to his secret, but Dimmesdale still refuses to reveal it. When Dimmesdale falls asleep, Chillingworth pushes aside Dimmesdale's shirt and sees something there that gives him joy. The narrator likens Chillingworth's touch to Satan stealing a soul.
Chillingworth, like the Puritans in general, maintains the appearance of righteousness but is actually a sinner, and feeds off the sins of others.