Lost is a mutant with the ability to nullify gravity around herself. As a side effect of her power her body greatly changed from the norm. When she lost her power during Decimation, she retained the physical changes. Being forced to live under normal gravity now, she was in constant agony.
When Lost was still young, her parents were killed during an attack by Fabian Cortez and the Acolytes. Lost would harbor a deep hatred for Cortez over the death of her parents. At some point. Lost caught the eye of the anti-mutant organization, Orchis. They took her in and experimented on her on multiple occasions, before finally using her to smuggle Onslaught into the mutant nation of Krakoa. In the hopes of limiting Onslaught's power and to allow the entity to avoid detection, they attached it to Lost, specifically to her hatred of Cortez.
Onslaught
Unaware of what had happened to her and what she carried with her, Lost travelled to Krakoa in the hopes of regaining her powers and finally alleviating the pain she constantly felt. Knowing that the Crucible would require her to battle to the death, she turned to Nightcrawler for help, feeling that he would be merciful and would give her quick and easy death. Unfortunately, Kurt was too distracted by his own troubles, and did not understand her request until it was too late. Magneto became her opponent in the Crucible instead and she was brutally beaten before death.
She was resurrected by the Five and happily regained her powers. However, her power also made everyone around her nauseous and start vomiting, so she quickly escaped from The Hatchery in tears. While on Krakoa, Lost came upon Cortez, who had also travelled there. With her hatred boosted by Onslaught, who had begun to infect the Krakoans, she attacked him. The fight was broken up by Legion and Nightcrawler, who were hunting Onslaught.
In an effort to help Lost, Nightcrawler attempted to bring her and Cortez together. They immediately began fighting, prompting him to teleport them 10 KM above Mars' surface; Lost could save them both, or Cortez could ensure they both died by blocking her power. Nightcrawler vowed to stop them from being resurrected unless they talked; the two began to speak, but before they could reach a conclusion Onslaught asserted itself. It seized control of the two, prompting Cortez to boost Lost's power until she died, and prompting her to use her powers to drag the moon of Phobos down towards the surface, dooming everyone on Mars. Nightcrawler, together with Cortez, managed to avert the crisis and teleport the moon back into orbit. Lost, in turn, was resurrected again.
As part of their plan to stop Onslaught once and for all, before it could use its influence to orchestrate a massacre that would restore it to full power, Legion and Nightcrawler secured Lost and Cortez, bringing them into an astral plane within Legion's mind. There, Nightcrawler finally prompted Cortez to reach a breakthrough, and reveal the self-loathing that had driven his crimes. Moved by his confession, Lost was able to let go of her hatred, drawing Onslaught out from its hiding place and allowing the Krakoans to defeat it.
Lost and Cortez were later seen together, preaching Nightcrawler's new philosophy; "the Spark".
Personality
--Since she has lost her powers she believes herself to be lost. She felt that she had no direction and was missing a part of herself. When she regained her powers she still felt herself to be lost due to her inability to be around other people, because her powers make them nauseous.
Powers and Abilities
Powers
--Gravity Destabilization: She constantly destabilizes gravity around herself and apparently can't control her power and can't cancel this effect.
--Floating: This effect makes her body weightless and allows her to float. --Nausea Inducement: Her power is shown to unintentionally affect the inner ear of people around her that then causes them to vomit uncontrollably, she has stated that she has no control over this ability.
Weaknesses
--Extreme Ectomorphism: Lack of gravity affected her body structure, greatly elongating and thinning it and all her limbs. Due to this, under normal gravity she feels extreme pain.
