"I just wanted to understand if this dream was really happening, or if it's just…a dream."
"What is real, and what isn't real doesn't matter here. What matters is what's true."
Katherine was a single mother of a boy named Michael. She loved him dearly, but she had a slight drinking problem and he…got in the way. Katherine's heart was in the right place as a mother, but eventually child services got involved and they took Michael away. Not long afterwards, Katherine was diagnosed with Medusa, a disease that slowly turns its victims to stone.
Meanwhile, as scientists desperately researched a cure and nearly the entire population became infected, Sir Henry Abstein offerred up a restored chateau for a cryogenics facility. One hundred and sixty cryo-sleep capsules were designed, manufactured, and installed. To fill these capsules, millions of people entered in a lottery. Katherine was one person chosen. The hundred and sixty winners were given indicator bracelets — once the white film turned black, they were in the final stages of Medusa — and then put under, awaiting the day that scientists would find a cure.
That day never came. Some time later, the capsules opened to a world covered in thorns. Parts of the chateau seemed to have collapsed. No person other than those put to sleep could be found. And it got worse. Once everyone woke up, they bolted for the elevator to get upstairs. Anyone who went for the elevator was promptly eaten by the faceless, shapeless mass of a monster lurking inside it. Om nom nom.
Seven people survived: Katherine, whose indicator bracelet was almost completely black; a hacker named Marco; Ron, the token black guy; the designer of the cryo capsules, Peter; an unnamed senator who bought his way into a capsule; Tim, a child who reminded Katherine of her own Michael; and lastly, a small Japanese girl named Kasumi, the real protagonist of this series. Finding themselves stuck together and without any sort of outside contact, the small band ventured through the chateau for answers.
The chateau was overrun with dinosaur-like monsters and gigantic fish. Somewhere over time, any and all scientists occupying the facility had disappeared. A safehouse full of supplies also yielded thorns and corpses. From there, the party went back to the chateau and tried to get to the bottom of things. Loooooong complicated wtf story short, we cut off with Katherine trying to save Kasumi, who is dangling off a cliff.
Katherine arrived in Nautilus disoriented and terrified. One moment she was holding onto Kasumi's arm, the next she was in a random city. She quickly calmed down when she learned that Kasumi was probably safe. After that, Katherine almost immediately began to work on Bending. A similar power existed in her own world, so she picked up on it rather quickly.
UHHH when I have more time
Medusa is a space virus. It crashed to Earth years ago, in the form of a meteor that landed in Siberia. Patient Zero was a small boy, who in turn infected his whole family. His sister, Alice, at the time no older than eight, was the only one to truly manifest Medusa. She brought her imaginary friend Laloo to life. Laloo stabilized himself by eating the family's pet reindeer. Afraid of this newfound power, Alice set fire to her family's home, killing Laloo. The rest of her family had already died. The fire spread the virus to the rest of the world.
Medusa isn't a disease so much as it is a power. Most humans, however, can't contain it, and it kills them. It takes someone of strong mind and will to manifest Medusa, which essentially means Medusa is this world's form of bending. Most of what is brought to life by the disease is horrific and beastly, because it is uncontrolled—the people who manifest that are typically people under extreme stress.
Katherine was the first in the survivor group to succumb to Medusa. But by that point, she knew what Medusa — and therefore Katherine herself — was capable of, and she used it to transform herself into a harpy. In this form, she saved the remaining survivors from an octopus monster. The harpy form is a part of Katherine now, and in Nautilus, she can freely switch between it and her human self (though typically once per day).