The Dragon is a spawn of Set, and claims to have killed the inhabitants of Titan before the arrival of the Eternals. Centuries ago, the Dragon attempted to conquer Earth, but was defeated by the Eternals. During the time of Camelot, the Dragon allied himself with Mordred. During the final battle between King Arthur and Mordred, Arthur helped the Interloper defeat the Dragon and banish him to space. With the assistance of Merlin they imprisoned him on Titan. Shortly later an artifact was created to keep the Dragon from returning to Earth under his own power.
From its prison on Titan, he sensed the mind of a human girl being raised there, Heather Douglas. During Heather's studies, she sensed "brooding, malevolent spiritual presence - hiding behind barriers." She destroyed the barriers and confronted the Dragon. During their confrontation it invaded her mind, but she rejected it untold he tempted her with its power, and told her she couldn't resist. Because of some of the barriers still in place she was able to shut him out, but the Dragon took refuge in her mind. Heather took the name Moondragon to show that she could overcome the Dragon's evil. The Dragon chose Moondragon as his vessel because she was powerful and basically good. But she was flawed with an arrogance he could exploit.
Mayor Story Arcs
During Moondragon's time on the Defenders, Moondragon started to struggle with keeping the Dragon in check. In one of their battles the Dragon manifested as a demon and told her that she couldn't master both good and evil, and no hope of winning. It then switched forms to that of Mantis and psychically assaulted her. The Dragon as Mantis then knocked Moondragon into a room with the rest of the Defenders. The Defenders battled "Mantis" until Beast manged to wake up Moondragon, causing "Mantis" to disappear.
Moondragon began meditating daily to control the Dragon, but she fell ill to the Gamma Spores. He then started taunting her with memories of her parent's death, and appearing to her in mirrors. When Moondragon discovered how the Gamma Spores were ravaging her body the Dragon claimed he could cure her. He then taunted her with images of her being rejected by all those she loved. She finally gave in to the Dragon, and he cured her. Now in possession of Moondragon, he attacked Angel, Gargoyle, and Valkyrie. After proclaiming his freedom he made Gargoyle fight himself, blinded Angel, and destroyed Valkyrie with a single blast.
The Dragon the consoled Moondragon, saying that he took full responsibility for the death of Valkyrie. Moondragon fully surrendered, and released the Dragon totally. When Beast, Iceman, and Cloud returned he destroyed their ship. The Dragon continued to taunt Moondragon as traveled on a path of destruction, until he was stopped by a giant manifestation of Valkyrie. The Dragon then surrounded Moondragon preparing to use the Earth's core as a weapon. The fire from the core shot into space, destroying part of the atmosphere. Valkyrie put out the flame and called in the entire Valkyrior. Angel then flew Cloud into the Dragon and found Moondragon. Cloud unleashed a lightning bolt causing both Moondragon and the Dragon to disappear.
Later Moondragon appeared on a ship with a manifestation of the Dragon overhead taking control of her again. The Dragon then appeared as two eclipsing suns as Moondragon attacked the Defenders, threatening to destroy them. The Dragon, through Moondragon, explained to each of the Defenders why they were going to die. When Interloper revealed himself the Dragon appeared in the sky over Moondragon. As the Interloper attacked the Dragon, the rest of the Defenders fought Moondragon. Manslaughter used his psychic link with Moondragon to project madness into her mind, causing her to flee, taking the Dragon with her.
The Dragon struggled to take over Moondragon again, but she resisted until the Dragon promised to put her in contact with the Beyonder. The Beyonder invited her to be his disciple, and turned the Dragon into a ring that she wore on her finger. Now with the power of the Dragon and the Beyonder, Moondragon decided reshape the world, starting with the death of the Defenders. The Dragon now in power again tormented Angel, Beast, and Iceman with the deaths of Candy Southern, Chris Larmouth, and Carol Faber. He used Moondragon to gain the trust of Gargoyle, then cast out his human spirit. The Dragon then also took control of Gargoyle's body. While the Dragon was focused on battle, the Interloper and Valkyrie gave up their forms and channeled the power through Andromeda and Manslaughter. After the blast, the Dragon and Gargoyle's bodies were destroyed. Moondragon then used the Beyonder's power to restore Candy Southern, Chris Larmouth, and Carol Faber.
Later, Dr. Strange, in battle with Urthona, destroyed several mystical talismans. One of them being the one that kept the Dragon from appearing on Earth under his own power. The Dragon made his way to Earth from a limbo when he sensed the weakened barrier. The Dragon then gained control over a group of skinheads in Manchester England. Strange used the Eye of Agamotto on one of the skinheads revealing the Dragon's influence. The minions were then stopped by a reincarnated King Arthur. The Dragon then took control of the Revolutionary Action Committee, having then take over a nuclear power plant. King Arthur managed to free the minions again. Dr. Strange and his fellow heroes all joined hands and formed The Dragon Circle. A giant sword appeared and fired at the Dragon causing him to shrink to the size of an insect and he was then crushed by Arthur.
Recently, Moondragon, concerned by the headaches she was having and fearing that the Dragon might be back, visited the Priests of Pama, and learned that he was back. She learned the only way to control the Dragon was to embrace the evil instead of denying it. During a battle with the Phalanx, Moondragon turned into a large black dragon and started to destroy the Phalanx. Moondragon soon became comfortable with the transformation and could still communicate telepathically. Moondragon in dragon-form helped Quasar defeat the Phalanx and save Adam Warlock. They were then attacked by Ultron, who killed Moondragon by ripping her heart out.
Guardians of the Galaxy
Recently Drax and Quasar went on the search for Cammi (a earth girl who was lost during the Annihilation War) but instead found out that Moondragon was still alive, which brought them to Mentor who killed them to send send them to Oblivion. There Quasar's Band's fell off because she had died and upon Drax finding out about this, they are attacked by Maelstrom but they defeated him and Maelstrom introduced Drax and Phyla to the Dragon of the Moon. The Quantam Bands find Maelstrom and attach to him thus giving Maelstrom the power to defeat Drax and Phyla and feed them to the Dragon, Maelstrom fed Phyla to the Dragon but she was able to cut her way out of the Dragon's stomach with Moondragon in her arms.