The Uranians were an intelligent non-humanoid race of beings that resided within the core of Uranus where they lived as part of a hive mind. Much of their history remained unknown except that millions of years ago their world was visited by a species of humanoids. These individuals were Eternals from the neighboring planet Earth that were criminals who attempted to overthrow their peers. For their actions, these specimens from an advanced offshoot of mankind were banished and sent into exile. Eventually, they arrived at Uranus where the native Uranians allowed them to inhabit their world. However, the Uranian Eternals were forbidden from leaving the planet and restricted as a prisoners to the domed settlement of Urania that was now to be their home. In exchange for living on the planet, the Uranian Colonists would provide by-products that the native Uranians could use. One of the terms of this pact between the two species was that the Colonists were forbidden from returning to Earth and if they did so then they would be stopped.
Despite these strict terms, they did allow for some lenient as the Colonist Eternals were allowed to communicate with Matthew Grayson during the on-set of World War II and even helped provide him technical plans to create a starship to reach Uranus. Thus, in the 1930s, both Matthew Grayson and his son Robert Grayson came to Uranus where they lived among the Uranian Eternals. In truth, this was part of a long term deception by the Colonist Eternals as they intended to use the young Robert Grayson as an emissary to Earth in order to establish an embassy from where they could bring about their return to their ancestral homeworld. As a result, the young Grayson was equipped with advanced technology and sent to Earth to become the superhero Marvel Boy in the 1950s. However, they came to realize that they could not control their 'ambassador' and initially killed his father where they masked his death to get Marvel Boy to stay on Uranus. He refused and sought to return to Earth whereupon the Eternal Uranians prepared for his replacement; one of their own known as Thelius who looked like Grayson who was being groomed as his replacement.
Despite their machinations, the Native Uranians believed that the pact had been violated and thus exterminated the Colonist Eternals in what appeared as a natural disaster where radiation emitted from the planet's core. This act unwittingly activated Thelius who became deranged as and took the name Crusader where he died in a mad attempt at avenging his people on Earth. At the same time, Robert Grayson came to Uranus where he learnt the truth about the Colonists after the headband technology allowed him full access to their history. With his technology failing, Grayson approached death when the unexpected happened which was the Native Uranians approaching him with an offer that they had never given anyone in the past. As Marvel Boy was human, it meant that he was outside the terms of the pact and that the Native Uranians could offer to help him. They offered to transform him genetically to become part-Uranian with the ability to join their hive mind. He ultimately agreed and remained within a Native Uranian membrane for decades before emerging. The changes to his physiology also meant that he now could only breath an atmosphere that mimicked that of Uranus and could only eat food by distending his esophagus.
Despite being part of the hive mass, he was still a separate entity and allowed to operate semi-independently. In order to take part in the physical world, he began the construction of a flying saucer starship even though Native Uranian culture forbade them from leaving their home planet. In the modern age, Robert Grayson received M-11's transmission and learnt that Jimmy Woo's life was in danger from Gorilla-Man. Thus, Marvel Boy did the unthinkable which was abandon the Uranian hive-mind in order to travel to Earth to safe the life of his old friend. This act meant that he would never be welcomed into their membrane again whilst he returned to his birth world to join the Agents of Atlas.