The Dragon is a enigmatic female member of the Vampire Council. She is an old vampire, having created Primo in ancient Roman times and seems to have been one of the original vampires, or at least one of the original bloodlines of Vampires. The Father of the Day stated all vampires descended either from him, Marmee Noir, Belle Morte, or the Dragon.
She has the power to draw all of the energy from another vampire, killing it permanently. Like Belle Morte and Morvoren, the Dragon feeds on emotion; specially anger and violence. Also like Belle and Morvoren, the Dragon can project her power, and did so in an attempt to force Anita to feed on Jean-Claude's vampires.
In Blue Moon, Damian states that the Dragon had formerly sired many vampires, but has remained largely secluded during recent centuries. In Incubus Dreams, the Dragon sent Primo to St. Louis in an attempt to dethrone or destabilize Jean-Claude. Once Jean-Claude and Anita overcame Primo, the Dragon permitted Primo to remain as their servant and expressed a desire to discuss "Council business" with them.
In Bullet, it is revealed that the Dragon along with the rest of the Council have taken the power of Marmee Noir into themselves, opening a way for the Mother of Darkness to posses them all. Marmee Noir could not actively posses her, but the Dragon sends some vampires from her bloodline to St. Louis just in case she becomes possessed. Those vampires would allow Anita to free her from the Mother of Darkness just as Anita did for Belle Morte and Padma.
The Father of the Day describing Belle Morte, Marmee Noir and the Dragon: "Belle Morte's line has powers that neither she, nor I, possessed. Belle was something new. All the others descend from us, but her and the Dragon. She was never human to begin with, so she was always different from us."