Dickens desribes the "Monseigneur, one of the great lords in power at the Court, [who] held his fortnightly reception in his grand hotel in Paris. Dickens uses this character to reveal the lavish lives of the aristocracy with details such as:
"It took four men, all four ablaze with gorgeous decoration, and the Chief of them unable to exist with fewer than two gold watches in his pocket, emulative of the noble and chaste fashion set by Monseigneur, to conduct the happy chocolate to Monseigneur's lips."
Dickens mocks the conspicuous consumption of the Monseigneur who is so high and grand that he needs four attendants to help him drink his cocoa.
The most important role the Monseigneur plays is that he acts as a catalyst for a key event in the novel. As the Monseigneur entertains his guests at the hotel, which consisted of him making a brief, snobbish appearance and leaving, he snubs the Marquis de Evremonde. The Marquis denounces the Monseigneur and leaves in a huff, ordering the carriage to be driven very quickly through the streets.
Evremonde's carriage ends up striking and killing a child, and Evremonde handles the situation very harshly, tossing a few coins at the grieving father Gaspard and witness Defarge. The child's death at the hands of the Marquis will become a major point of contention for the leaders of the rebellion who will seek revenge from the Marquis and his family.