Delroy Garrett, Jr. grew up to become a track star and competed in the Olympic Games. After he tested positive for steroids, he lost his three gold medals. In despair, he turned to religion, specifically the Triune Understanding. This group's founder, Jonathan Tremont, had found one of three fragments of a mysterious object and used it to give Garrett the powers of 3-D Man. Garrett assumed that his powers were because of his newfound spiritual enlightenment, and Tremont never disabused him of the notion.
Triathlon served as the Triune Understanding's spokesperson for a while. While at JFK Airport, he witnessed the capture of the Avengers by Moses Magnum and freed them. He crossed paths with the Avengers again when Lord Templar and Pagan disrupted the dedication of a Triune Understanding facility, during which the facility sustained heavy damage. Tremont launched a public relations campaign that painted the team as biased and irresponsible, which was only a ploy to force them to recruit Triathlon. It worked. Either because he believed Tremont's public statements about the Avengers or because he felt sensitive about his standing, Triathlon had difficulty fitting in at Avenger's Mansion. With time, though, he developed friendships with Pulsar and Warbird and got past his initial hostility.
While Kang the Conqueror was conquering Earth, a giant pyramid arrived from space. Triathlon learned that the universe had somehow created three artifacts as a response to this Triple-Evil; that Tremont had set up the Triune Understanding as a means to locate the three artifacts; and, most important, that he and Tremont both possessed a fragment. The Avengers (including Triathlon) and Tremont boarded the pyramid. Only then did they learn that Tremont, instead of hoping to destroy the Triple-Evil, wanted its immense power for himself. Triathlon refused to give up his fragment, and when he found the third fragment in the pyramid, he took Tremont's fragment. Uniting all three fragments gave him the power to seize control of the pyramid and defeat Kang (with a little help from the Avengers). Soon afterward, Triathlon (as well as others) left the team when it was restructured. He also left the Triune Understanding...
