Robert Grayson was born in the 1930s, the son of scientist Professor Matthew Horace Grayson and wife, Marna, in Germany. Horace was a rocket scientist who worked for the government. However, when Hitler rose to power, Grayson did not support the ruling Nazis but was forced to continue his work. His wife lived in constant fear due to her Jewish ancestry and when this was learned by the Nazis, she was killed. Robert was spared, and his father Horace continued to work on a means of escaping the Nazis. He constructed a radio that beamed messages out into space.
Professor Grayson made contact with the Uranian Eternals, who provided him with the knowledge to build a rocket to escape Nazi Germany with his infant son Robert. The Eternals on Uranus then welcomed the Grayson family with open arms, raising Robert as one of their own. The Uranian Eternals were secretly plotting to re-establish ties with the planet Earth in an attempt to be reunited with their planet of origin and influence the society there into what they viewed as a utopia. Monitoring the progress of the War on Earth, the Uranian Eternals waited for the ideal opportunity to begin their agenda, and upon witnessing the activities of Earth's super-soldier Captain America decided to groom Robert into the image of a superhero the people of Earth could relate to; in other words, their ambassador to Earth.