John Ryker joined the military at a young age. He wanted to help determine future history from the shadows. One of his most prominent actions was manipulating the creation of the conspiracy around the assassination of President John F. Kennedy. Apparently, Kennedy was really killed by two Austrian mercenaries, but at the time it was deemed too expensive to wage World War Three so the idea of a conspiracy was created.
When he learned that his wife Lucy has cancer, Ryker used the military to hunt down Bruce Banner. He knew that Banner was really the Hulk and he was hoping to isolate the Hulk's ability to cope with radiation and use it to heal his wife. However, Ryker's wife didn't want any part of finding a cure if it involved in harming, or even killing, an innocent life. This eventually lead to becoming an obsession to capturing the Hulk. To increase his chances of capturing the Hulk, Ryker also developed a team known as the Gamma Corps, which involved a small team of soliders mutated by gamma radiation.