Natalie X comes from a future where the Earth is dying. She, along with all the remaining heroes and villains of her time, formed the New Defenders to find a solution to the problem and save the remaining inhabitants of Earth. Battling and capturing Galactusto power a time machine, Natalie is one of only seven that survived. She formed a relationship with Alex Ultron, as she could not read his thoughts.
Natalie came with the remaining heroes to the past to capture Doctor Doom and the Human Torch to help power the Galactus Engine, which would be used to bring the remaining billions on their Earth to the past. Being the most powerful telepath of her time, Natalie was able to subdue the mighty Doctor Doom by implanting many nightmares into his psyche.
The Fantastic Four stopped their plans and instead transported the future refugees to an artificial planet called Nu-World. But the creator of Nu-World, Ted Castle, did not appreciate them being there and destroyed the portal off the planet. After they battled him, they reformed as the Fantastic Force. Just then, they were attacked by the Harpy, which Natalie could tell was being mentally blocked from her.
She soon learned why. She was one of the Hysteries, formed by Gaeato bring her people back to her on their dying world. Natalie was no match for the Dark Phoenix's mental powers, but she was allowed to leave and try to convince the others to send some of the people back to Gaea. She was unable to do so, but Hulk Jr. was able to send them back to their respective times.
Next, Gaea sent Ego the Living Planet to destroy Nu-World. Natalie, along with Alex Ultron and Psionics, went to face Ego themselves. Natalie used her power to unlock Psionics' full potential, where she gave Ego a massive stroke and stopped him.
It seemed all the troubles were in the past until the sun collapsed on itself and formed a black hole. This caused war among the residents of Nu-World. Under the leadership of Lightwave and Alex Ultron, they used Natalie X's telepathy to control as many of the populace as she could handle eventually achieving a perfect socialist state.
They experimented on her using cybernetics and Mutant Growth Hormone expanding her power into a worldmind. Eventually containing all of the citizens of Nu-world in her mind, she was evacuated to earth when Nu-world was destroyed by a vengeful 616 Galactus.