|“||Valentine Morgenstern drew a circle of friends together: young, idealistic Shadowhunters, to help him steal the Mortal Cup from the Clave. But he didn't want to protect humanity. He believed there had to be an evolution of Shadowhunters... something more powerful.||”|
During its formation, the members consisted of young idealistic Shadowhunters. Because they were mortal and their enemies—the demons—were hard to kill and increasing in number, Valentine was easily able convince his followers that the Mortal Cup should be used to create more Shadowhunters—something that the keepers of the Cup, the Clave were afraid to do because of the risks. Taking matters into their hands, the group followed Valentine and helped him steal the Cup.
However, Valentine eventually took on a more radical agenda: aside from just creating new Shadowhunters and wiping out demons, he wanted to eradicate Downworlders and allow Shadowhunters to evolve into more powerful beings—something he tried by performing experiments with demon blood and the Cup. Instead of performing the Shadowhunter mandate to protect humanity, he aimed to rule, and even resorted to using demons for his goal.
Most of his original followers eventually abandoned Valentine and the Circle. To put a damper on his plans, his wife Jocelyn stole the Cup and went into hiding, and Valentine and his remaining followers have been on the hunt for her since.
- The Circle was never named in the film adaptation; instead, in the film, they were referred to as a "circle of friends" that Valentine drew together. They were named in the film's companion book, Shadowhunter's Guide.