General John Ryker is rumored to have been involved in a U.S. President's assassination, and he possibly dropped the toxic Agent Orange chemical on army soldiers simply to study its effects on them. He considers the men under his command expendable, and he can brainwash nearly anyone to obey him.
Ryker's wife, Lucy, was dying of cancer, and he was trying to cure her using gamma radiation. Becoming obsessed with the Hulk (Bruce Banner), he was determined to unravel the secrets of gamma mutation and began experimenting on many homeless individuals, all resulting in painful deaths. Discovering the key to success might coincide with the subject's mindset, he experimented on his own troops. Ryker's first triumph was a mentally unstable private, Benjamin Tibbets, transforming Tibbets into Flux. Manipulating Flux into thinking the Hulk was responsible for his deformed makeover, Ryker directed Flux's anger at the Hulk but Flux was defeated. General Thunderbolt Ross, long-time enemy of the Hulk, uncovered Ryker's real agenda, and told Lucy; who was appalled at her husband's behavior for ruining innocent lives with his experiments.
When Lucy died, Ryker became more enraged at the Hulk's existence and started his research again. Transplanting superhuman tissue onto normal humans, the five individuals who survived the ordeal became Ryker's Gamma Corps. Using DNA from Hulk foes such as the Abomination, Leader (Samuel Sterns), the Harpy, Doc Samson and the Hulk himself, Ryker created the operatives Mess, Prodigy (Timothy Wilkerson), Griffin (Eliot Franklin), Mister Gideon, and Grey. Gamma Corps was trained to kill the Hulk, but the Hulk they encountered was different than the one Ryker was familiar with. Although nearly achieving victory, the Gamma Corps was defeated. Hulk again exposed Ryker as a master manipulator that hid the truth from his subjects, and the Gamma Corps rebelled. Ryker was captured by Gamma Corps and jailed in a SHIELD penitentiary.
After the war with the Skrulls ended, and Norman Osborn was appointed commander of every military and research facility, including SHIELD, Ryker was released from prison and made CEO of Osborn's Origins Corporation because of Ryker's previous successes with transplanting tissue from powered individuals into civilians. Ryker was tasked to hunt and capture Hulk's daughter Lyra for DNA samples and acquire her sentient computer Boudicca. Again using tissue from the Hulk's enemies – Abomination, Zzzax and the Glob – Ryker created three more agents – Aberration, Axon and Morass – to serve in his new Gamma Corps: Black. Ultimately failing their mission, Morass and Aberration were killed by Lyra, and Ryker remotely terminated Axon.