Bob Grayson was just a baby when his father, an astrophysicist, managed to make contact with a colony of Eternals on the planet Uranus. His father feared what Earth was becoming as Adolf Hitler began to rise to power, and he looked to the stars for comfort instead. The Eternals helped him build a spaceship, and he and his son left Earth to make Uranus their new home. The Eternals helped Bob reach the peak of his potential, but he nevertheless longed to return to the planet of his birth. When he was seventeen, his father relented. The Eternals gave him a personal spacecraft called The Silver Bullet, wristbands that could be used as a defensive weapon, and a tunic that would evoke Apollo, the god of light. His father urged him to use his powers as a champion of the Uranian lifestyle of peace and harmony, and Bob became the superhero known as Marvel Boy! Marvel Boy fought crime for many years, enjoying great fame and favor. He even became an agent of the U.S. government, recruited by Jimmy Woo to join other heroes in one of the first super-teams. He welcomed the direction, feeling it was the culmination of his life so far.
Shortly after Woo's team of heroes disbanded, Marvel Boy received a distress call from Uranus. He arrived to find the city destroyed, but he also learned the horrible truth about his origin. The settlement was a penal colony for rogue Eternals who once tried to conquer Earth and the native Uranians, living in the planet's core, supervised the Eternals so that they wouldn't try to return to Earth. That's why the Eternals helped Marvel Boy and his father-- they saw them as a loophole to be exploited. Ultimately, the Uranians disagreed, causing the Eternals' destruction. Marvel Boy would have died as his Eternal technology failed him, but the Uranians took pity on him and accepted him into their number. Unfortunately, because the Uranians lived as a communal organism, Marvel Boy had to be genetically reborn, and he spent decades in a membrane/chrysalis.
During the Eternals' destruction, they rushed to completion a duplicate of Marvel Boy. The duplicate arose too late to be of any help, however-- it was born an unstable creature with false and fractured memories. It believed that the Eternals' protective dome was destroyed, and it was the fault of bankers of Earth who stalled him when they denied his request for a loan to purchase medical supplies for his father. He rushed back to Earth to exact revenge, calling himself the Crusader, and he began a rampage. The Fantastic Four intervened, but it was the Crusader's misunderstanding of the Quantum Bands he wore that made him reckless. He absorbed so much energy that the bands overloaded and his body was destroyed.
For years, Bob Grayson lived a solitary existence, despite the Uranian collective, since he regarded himself a separate entity by nature. He passed the time by building a new flying saucer, although the Uranian culture forbade him from leaving the planet. Still, when he received a distress call from former allies M-11 and the Gorilla Man about the near death of Jimmy Woo, Marvel Boy decided to return to Earth to help. Unfortunately, this meant leaving Uranus and severing his ties with the collective for all time.
Marvel Boy was instrumental in reviving Jimmy Woo, and he joined Jimmy and his former allies in completing the search for the Atlas Foundation. Ultimately, Jimmy took control of the Foundation, professing his determination to use its resources for the betterment of the world. He, Marvel Boy, and the other Agents of Atlas would become a clandestine force for good.