Amelia was a mutant born with the ability to transubstantiate solid matter into vapor. She left her home and her family to get away from their hatred of her mutant gifts. She became a nurse and travelled to India.
Here, she met Charles Xavier, a fellow American who had lost the use of his legs. Amelia cared for Charles after his injury, and her positive and friendly attitude helped Xavier get over his depression. The two quickly fell in love, and shared an apartment in Bombay. Unbeknownst to Amelia, Xavier was a mutant himself, and his encounters with other powerful mutants such as Magneto and the Shadow King had made him obsessed with building a machine to track mutants, hoping to protect and educate them, so they wouldn't turn into threats to themselves or others.
Amelia found the plans and thought that Xavier was developing the machine to hunt down and exterminate mutants. She revealed herself to be a mutant and attacked him, only to stop when Xavier revealed his own mutant powers.
This link strengthened their relationship even more, but over time they both developed different stances on human-mutant interaction. Xavier wanted open co-existence with humans, while Amelia thought it was best for mutants to hide themselves. When Xavier brought Scott Summers to his mansion for training, Amelia left him, telling him that his plans for the X-Men would only lead to a genetic arms race and ultimately doom mutantkind. Panicked, Xavier used his powers to compel her to see his side of the issue. He quickly stopped himself, but the damage was done, and an angry and hurt Amelia left him.
She stayed hidden for the next few years until human-mutant relationships deteriorated further. She joined the Acolytes, followers of Magneto, whom she had met with Xavier years before. As one of the older and more experienced mutants, she was given a position of seniority within the group, even though she didn't agree with some of the Acolytes' more extreme policies, such as the killing of humans. Over the years she supported the Acolytes and Magneto, but she also tried to limit casualties, and gave limited aid to the X-Men and other superheroes, for example Magneto's son Quicksilver who opposed them.
In fact, she attempted to quit the Acolytes a number of times. Fabian Cortez attempted to use an amnesiac Magneto to gain control of the Acolytes. With Amelia's help, Cortez was defeated and Magneto did not return to his villainous ways.
She was offered a place on Genosha by Magneto, and was still there when the Giant Wild Sentinel attacked the mutant nation, unleashed by Cassandra Nova. She was incorrectly presumed to have perished in the attack.
Amelia was one of a handful of mutants to retain their powers following the events of M-Day and returned to working as a nurse, this time briefly at Sacred Heart Hospital in California.
After Bishop mistakenly shot Charles Xavier in the head while trying to shoot Cable, Amelia was working with Exodus and his Acolytes to repair Xavier's seriously damaged mind. She made peace with Xavier after he convinced Exodus to stop the internal mutant wars and disband the Acolytes. She relocated to San Francisco where the X-Men offered protection to the mutants, along with her teammates.
Amelia was with Exodus and other Acolytes when they were first greeted by a hologram of Professor X, then later when they were seen on Krakoa among other X-Men villains and foes. As Professor X's hologram was conversing with them, around the world he was also greeting and conversing with other mutants, welcoming them into the country of Krakoa.
Amelia would later appear as a member of one of S.W.O.R.D.'s sub-teams, the Teleport Team, a group of mutants with teleportation powers, to aid S.W.O.R.D.'s commander Abigail Brand and their other sub-team The Six.
