Certainly, Dickens pulls no punches in describing how badly the Marquis St. Evremonde abuses his power as a member of the ancien regime. The rape of Defarge's sister, the dismissive manner he carries towards his own citizens, and, of course, the running over of Gaspard's child without the least bit of remourse reflects Evremonde's abuse of power. Dickens describes him in terms and situations that reflect the ultimate in uncaring of political leaders. It almost becomes a logical conclusion that with such leadership abusing the public trust that revolution would become inevitable. I do believe that the counterpart that ascends to power as a result of the Revolution, the forces of blood lust as embodied by Madame Defarge, also represents an abuse of power. Madame Defarge is so driven by power and revenge and consumed with position of being able to deliver the vengeance that she so seeks that she ends up abusing her power, as well, during the Reign of Terror. The reality presented is that any ruler that does not understand the principles of leadership and poltical rule can abuse the power they possess.
The two characters mentioned, the Marquis d'Evremonde and Madame Defarge, are, certainly, the main characters quilty of power as so well explained in the previous post. Other characters to consider are the Monseigneur and the Jacques and the Vengeance, characters who are more symbolic than real in Dickens's A Tale of Two Cities.
-----In Chapter 7 of Book the Second, Dickens describes the Monseigneur, who represents the powerful aristocracy that lives in luxury. He has the "truly noble idea that the world was made for him," and snubs the Marquis d'Evremond at his sumptuous ball:
Bestowing a word of promise here and a smile there, a whisper on one happy slave and a wave of the hand on another, Monseigneur affably passed through his rooms to the remote region of the Circumference of Truth. There, Monseigneur turned, and came back again, and so in due course of time got himself shut up in his sanctuary by the chocolate sprites, and was seen no more.
"I devote you," said this person [the Marquis d'Evremonde] ...to the Devil!"
Then, in his "inhuman abandonment of consideration," the Marquis leaves in the carriage that runs over the poor child as previously mentioned.
-----Throughout the novel, the Jacques and the Vengeance act as the paracletes of revenge against the aristocracy of France. For instance, they take an aristocrat and force him to eat grass, then run him across the countryside, and finally execute him. These new oppressors load the tumbrils with anyone who is suspected of association with the French aristocracy, even a poor seamstress, who "has done nothing."