|“||I hereby render unconditional obedience to the Circle and its principles... I will be ready to risk my life at any time for the Circle, in order to preserve the purity of the bloodlines of Idris, and for the mortal world with whose safety we are charged.||”|
–Loyalty oath, City of Bones
The Circle was formed by Valentine Morgenstern, who recruited his peers as early as their school years in Alicante. A bright and young Hodge Starkweather, who greatly admired and felt indebted to Valentine like the rest of its members, helped write the Circle's loyalty oath.
In the beginning, Valentine focused on reforming the Clave and increasing the number of Shadowhunters to fight demons, as well as living proudly among mundanes instead of hiding. Over the years of the group's existence, it grew in number, attracting at least half of the young Shadowhunters in Idris, and even some from other places, during their time.
However, after Valentine's father was killed by werewolves, his ideals changed, and so did the Circle's. From revolutionizing the Clave, its goals became the destruction of all Downworlders. Because some, if not most, of its members were fanatics who merely worshiped Valentine, the members remained, still partly believing in his cause, and that their acts and objectives were noble. They held demonstrations and protests to vocalize these claims.
Eventually, several of Valentine's followers left the group when they began to realize the extremity of Valentine's views and the brutality of his plans.
The Uprising took place in the Great Hall, during the signing of the Ninth Accords in 1992. Through an alliance with demons, the Circle was able to smuggle weapons in the Hall. The Circle tried to overthrow the Clave, killing several Downworlders and Shadowhunters present, believing that their goal was noble enough to justify their means. They hoped to ignite a war between the two sides and finally rid the world of Downworlders. However, the Downworlders were informed of the plan before the signing, by Jocelyn Morgenstern, who plotted to fight back by letting other Downworlders into the Accords Hall, led by her co-conspirator, Lucian Graymark.
After the Uprising, the Circle was disbanded by the death or escape of some of its members; even its leader, Valentine, was believed to have committed suicide in the Fairchild manor. The more loyal members fled, but some remained and testified for the Clave in exchange for clemency. They cooperated in the search for those who ran away and gave names of those involved. Several members continued to live among Nephilim society after that, including the Lightwoods, though with punishment; others were punished more severely, like Hodge Starkweather. Those who left the organization before the Uprising were let off easily.
For years, the Circle became a horrible part of the Nephilim's history. Since their existence has since been considered an embarrassment to the Clave, most documents pertaining to them were destroyed. The name became less talked about and almost lost among the new generation, to those who were not present during the group's existence. When Valentine was revealed to be alive, some of his very loyal followers from the Circle, like Emil Pangborn and Samuel Blackwell, were revealed to have known and have been aiding him for years.
Some time after, all remaining members of the Circle who were still loyal to Valentine met with his son, Sebastian, at the Seventh Sacred Site to summon Lilith. They drank from the Infernal Cup and became the first Dark Shadowhunters. A large number of this first batch were killed in the battle against the werewolves of the New York werewolf pack and the Shadowhunters of the New York Institute.
- Valentine had a way of tracking the members of the Circle through a Mark—a permanent one that's not in the Gray Book—on their skin; it could be as small as a tiny, almost invisible white mark under one's hair, as Maryse's was.