They are the closest things the moon has to Demons, but they are peculiar creatures of the Dark; just as the Lucen have the virtue of Angels but not their sense of civilization and order, the Nocten have the vice of Demons but not their drive to savagery and destruction.
The Nocten are sordidly obsessed with order, rather. Precise mechanics, never-ending clockworks, detailed classifications; they strive to master the untamable nature of the Silver Wilderness through the construction and application of their Shadow Mechanics. As the cycle of the Moon continues, they fight a never-ending battle with the Lucen, oscillating between victory and defeat since the dawn of time. From the Earth below, we simply see this as a cycle; very few people know that when the Moon is dark, the Mechanics have filled most of its insides, or that a Full Moon is caused by the shining roots of the Wilderness inside it.