Scaramouche, the King Maker is its much more dark and cynical cousin. Gone, for the most part, are Andre Louis' unending witty repartee and cutting come-backs. He is now pure Machiavellian schemer who seems to bring the downfall of the powerful as a whim and sends men (mostly scoundrels, but innocents also get caught as collateral damage) to the guillotine simply as a game or test of his skill. Despite being one of the best swordsmen in France, there is not a single duel. He never draws his blade. His mind and capacity to plot and exploit the weaknesses of powerful men is much more powerful.
We watch over and over again as he coaxes the wealthy and powerful out onto a limb, while he saws it off behind them with a cynical smile, taking no joy in his success. He has no true motivation, no principles----he does not support any cause, in fact he has contempt for those who benefit from his machinations. He just manipulates and wreaks havoc.
Yes, his love for Aline in a primary motivator, but I found his behavior to be disturbing and amoral. I think that might be what Sabatini was looking for. This novel is a condemnation of the French Revolution as well as how power corrupts all it touches. There are no heroes in this novel, really. All are protecting their own interest and whose head will fall into the basket is more a function of timing and which way the wind blows.
The King Maker is nowhere near as much fun as Scaramouche. It is sort of like The Unforgiven was to westerns---an adventure of the French Revolution without the romance and myth. Just betrayal, greed, the exercise of power, and the basest of human traits on display. In other words, it is realistic and a more complex and modern novel.