Nate Grey was created in an alternate timeline in which Apocalypse had conquered North America. Nate was created by one of Apocalypse's Horseman, Mister Sinister, from genetic material taken from Prelate Cyclops and the captive X-Man, Jean Grey. Nate was born and grew up in Sinister's slave pens, from which he was released years later by Cyclops, who had turned against Sinister. After his escape, Nate joined Forge, who led a traveling band of performers, who were secretly conducting guerrilla warfare on Apocalypse's minions in the American Midwest.

Sinister, realizing the damage that would occur if Apocalypse continued his reign, found and killed Forge. Sinister revealed to Nate who Nate was and why he was created: to destroy Apocalypse. In his grief over Forge's death, Nate lashed out with his psionic powers and killed Sinister. He then journeyed to Apocalypse's Citadel, located in what once was New York City. Nate found the X-Men, led in this timeline by Magneto, and helped them in their assault on the Citadel.

During the attack, Nate battled Holocaust by himself. Nate, in an attempt to breach Holocaust's armor, stabbed him with a shard of the recently recovered M'Krann Crystal, and both Nate and Holocaust vanished.

Through the powers of the M'Krann Crystal, Nate was transported to our Earth, landing in the Alps. When he first landed, his subconscious need for companionship recreated a physical body for the dissipated essence of the then-deceased Madelyne Pryor. Nate and Madelyne, who became fast friends, journeyed through Europe until Pryor was convinced to leave Nate by Selene, who wanted Pryor as a member of the newly reformed Inner Circle of the Hellfire Club.

After leaving Europe, Nate encountered McCoy, a twisted version of Hank McCoy from the timeline from which Nate originally hailed McCoy told Nate that he recognized Sinister's work, and explained that Sinister would not have created someone so powerful without a fail-safe. McCoy claimed that Nate's existence was to end the moment he accomplished his mission (to destroy Apocalypse), and Sinister designed Nate's psionic powers to kill him within a few years. To investigate this claim, Nate traveled to Muir Island, where Dr. Moira MacTaggert confirmed the diagnosis: his powers could indeed kill him before he turned twenty-one.

After this revelation, Professor Charles Xavier subjected Nate's mind to a probe. Sensing evil (the part of Xavier's psyche that would eventually break from Xavier and become the entity known as Onslaught), Nate lashed out with his powers and pulled Xavier's psyche from the astral plane.

Soon after that encounter, Nate saved the mutant Threnody, who was fleeing clones of the original Marauders, and the two began to travel together, finally settling in New York City.

Recently, Madelyne Pryor, who was now a member of the Hellfire Club, returned to find Nate, since she felt a connection. Pryor encountered and killed Threnody, and discovered that she (Pryor) had been reconstructed by Nate, later becoming independent of him. Pryor was felled by the combined effort of Nate and Phoenix, the Jean Grey of this timeline.

While visiting the X-Mansion, Nate met his future fiance, Amelia Pratt, under awkward circumstances. Amelia's silica attacked Nate and her and Nate ended up defending her against herself in a way. She was mortified but Nate thought nothing of it... they became friends... and then lovers, before finally becoming engaged.

A paradoxical being born of a reality that never will exist, Nate dedicated the totality of his talents to the preservation of his adopted homeworld. The promise of his powers fully realized, X-Man became a modern-day mutant shaman, existing to heal and guide his tribe, though forced to live outside it. He loved them as a parent loves a child, without question. A world-walker, he fought to protect the planet from the incomprehensible, impossible threats of the multiverse, parallel Earths strung along a spiral from one end of reality to another. To save humanity from destruction, he sacrificed himself for the greater good, allowing his energy to flow into every being on the planet.