What does Chillingworth do while Dimmesdale sleepes, and what does his action symbolize? What does his response reveal about his character?

Chillingworth sees the carving on Dimmesdale's chest. He dances around the sleeping priest in glee. Chillingworth is an insidious man. The symbol "A" on the priest's chest gives him the green light to torture this fellow. He doesn't seem concerned even with revenge rather than he enjoys the act of slow subtle torture itself.