As a young government agent, Cecil Stedman was trapped by terrorists and exposed to a flesh-disintegrating gas. He was rescued by Brit at the last second. In the aftermath, he had artificial skin applied to his entire body, except for a piece of his original, decayed skin around his mouth to always remind him that he had screwed up and allowed people to die.
Years later, the Lizard League invaded the Pentagon. When trying to escape the invaders, the two terrorists that had almost killed him before had appeared on the scene and saved him. Director Radcliffe revealed that their deaths had been faked, since he thought they were of better use working on the government's side. Subsequently, Cecil thanked the former terrorists by killing them on the spot, earning him a prison sentence on his own. After a couple of months, Cecil was visited in prison by Director Radcliffe, who was stepping down from his job on the Global Defence Agency, and claiming that Cecil would be the only person capable to take over. After declining, Radcliffe told Cecil that he could either be the good guy or the guy who saved the world, but not always both at the same time. Stedman soon accepted the offer.
Major Story Arcs
After a year as the head of the GDA, Stedman noticed Omni-Man battling an alien tentacle creature, and shortly thereafter, confronted him. Omni-Man wanted to learn the customs of Earth, something Stedman could grant. In return, Omni-Man explained a highly sugarcoated version of his Viltrumite origin, claiming to represent a "World Betterment Comittee" when in reality, he was an advance scout for an invasion. Monitor technology at Pentagon confirmed his alien origin, but concluded that his story was a lie. Cecil didn't care much for it, meaning that as long as Earth was reasonably safe, Omni-Man's reasons for lying hardly mattered. He would regret this later...
Many years later, Omni-Man revealed his true intentions about conquering Earth to his son Invincible. When Invincible (rather violently) disagreed, a battle of epic proportions ensued, all of their talk recorded by the earpiece the GDA had installed in Omni-Man's ear (to be able to contact him easier in emergency situations). Omni-Man left Earth shortly afterwards, showing little hint of a return. Subsequently, Cecil began to work Invincible much as he had worked with Omni-Man previously, with an earpiece installed to alert the young superhero of emergencies. At the same time, Cecil made sure that Invincible's mother, Debbie Grayson, wouldn't have to worry about economy (seeing as how her Omni-Man had been responsible for their family's income) or having their identities exposed.