While he is depicted as being a small and physically weak man, he is extremely intelligent and cunning, able to manipulate those around him and devise elaborate plots.
Also, his bitter hatred of Sir Percy has become an obsession and he wishes to be personally responsible for stopping the Pimpernel's interference in French politics.
However, Orczy reveals that Chauvelin has a more human side and fills in some background details - among other things, mentioning his first name, Armand, for the only time in the series - in the novel Sir Percy Hits Back which features his daughter, Fleurette.
Orczy's depiction is loosely based on Bernard-François, marquis de Chauvelin, a notable political figure in revolutionary France.
The historical Chauvelin was in fact a notable military officer who served with Rochambeau in the American Revolution, and as assistant ambassador to Britain in the time period depicted.