The setting sun's blush on the Marquis' face suggests what fate awaits him?

The setting sun, and the crimson blush upon his face fortell a bloody death by stabbing. The stain also reminds us that on his rampant ride through the city, his coach was responsible for the death of a young boy..... and in turn, the Marquis.

The Gorgon had surveyed the building again in the night, and had added the one stone face wanting; the stone face for which it had waited through about two hundred years. It lay back on the pillow of Monsieur the Marquis. It was like a fine mask, suddenly startled, made angry, and petrified. Driven home into the heart of the stone figure attached to it, was a knife. Round its hilt was a frill of paper, on which was scrawled: "Drive him fast to his tomb. This, from Jacques."

The sun's blush and the stain foreshadows a bloody ending for marquis who killed a kid in his way and thought it to be worthy of a coin, this in return gifts him the present of death.

It also foreshadows that all the aristocrats will vanish with blood turn by turn.