Gideon was a member of the first expedition led by Christopher Columbus in 1492, but he succumbed to the rigors of the journey, died, and was buried. However, Gideon recovered, his nature as a mutant External allowing himself to be resurrected. Although his subsequent history remains largely unrevealed, over the course of the next several hundred years, he became quite wealthy and discovered other Externals like himself. In more recent years, Gideon studied at Harvard but was expelled under circumstances to be revealed. He went on to build his company, Ophrah Industries, into a corporate giant, intending to use his ever-growing financial power to dominate the world.
Gideon first came to public notice when he began forging alliances between high-tech industrial consortiums, such as GeneTech and the Taylor Foundation, and with powerful mutants or secret organizations such as A.I.M. He is known to have formed an alliance with the Toad, who was leading the Brotherhood of Evil Mutants at the time, in a scheme to recreate the menace Proteus. Similarly, he joined a group of hedonists known as the Upstarts, although whether or not he carried through with their goals of killing mutants is unknown.
A long-time family friend of the DaCosta family, he erroneously believed the young Roberto DaCosta (secretly the hero Sunspot) to be the new immortal that the Externals had been looking for. Gideon manipulated events to have DaCosta's father killed and Roberto to take over the role as leader of the DaCosta’s family company. Gideon positioned himself as DaCosta's mentor, taking him away from his role in the team of New Mutants and into Gideon's confidence.
Until recently, Gideon kept his power a secret, preferring to work behind the scenes. However, the New Warriors, when investigating criminal links of the Taylor Foundation, caused Gideon to reveal his mutant powers and sadistic temperament. He soundly defeated them.
When it was discovered that Cannonball was the mutant Gideon was searching for, Gideon abandoned DaCosta, subjecting him to vicious experiments, until he was later rescued by the New Mutant's later incarnation, X-Force.
Surprisingly, Gideon sent a distress call to X-Force after being betrayed by the External Selene. For reasons of her own, Selene was suddenly killing the remaining members of the Externals, absorbing their life forces. Despite the efforts of X-Force, Gideon was the first External to be killed by Selene, when she drained him of his life energy.