Louis had been born into the de Sade aristocracy alongside the likes of Antoine, Veronica and Dominique de Sade, and was able to spend much of his time with the likes of Noé Archiviste, whom Louis' grandfather had purchased at an auction, and while he disagreed with Noé's position on the beauty of the Blue Moon, the two remained close friends throughout childhood.
He resulted being a curse-bearer and was beheaded by Noé's Teacher after he started attacking Noé and the others.
He was actually Dominique's twin brother, at the time they were born, one was meant to be killed as it is a rumor that they bring bad luck. Count de Sade chose his sister to survive, but Noé's Teacher said it would be a waste to kill Louis so he used him for an experiment, allowing him to live his childhood but making him become a curse-bearer and condemning him to die.