BIO still is a VERY early work in progress, subject to big changes as I create more characters and flesh out the story.
Also pardon any writing mistakes as English is not my main language and I'm still learning it, if you spot any grotesque grammar error please tell me!

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Name: Mabel Papel
Age: 20
Species: Human
Height: 1,66 cm
Weight: Used to be 65 kilos before, now barely reaches 2 kg on her transformed state.

Mabel is a geeky girl who loves video games and technology, being a really big fan of the interdimensional Gréuly industries and their new revolutionary gadgets and researches. So imagine her enthusiasm when her application to work for them was accept, she would finally be able to put her geekiness to better use than grinding on online games!

Despite her young age she did pretty well, apart from some days of coming late to work because of gaming-related sleepovers, her assistance on the laboratories and eagerness to help was greatly commended by everyone. So it wasn't very long until she was promoted into more important roles, one of them being joining their famous field-gatherers.
How happy she was, to enter portals and visit completely remote places and dimensions to gather precious materials not found anywhere at home!

And there she was, wearing a very large and spacious outfit that resembled one of an astronaut, meant to protect her from possible dangerous interactions and radiation from whatever place they went to visit.
With a big smile stamped on her face, she waited for the instructions of her first field mission. "We know your fame with eletronic videogames Mabel, so you are perfect to visit our newly discovered Flatland. This place greatly differs from ours as it lacks our third dimension of depth, making the entire place to be completely flat.
Because of that, locomotion becomes way more difficult, but with your expertise of playing 2D games like Super Plumber Bros, you are our best bet for this."
The manager said while commanding the other scientists to get the portal machine ready.
"We already managed to enter in contact with it's inhabitants, so all you have to do is to enter and retrieve the material packages from them, should be a safe field mission."
Mabel acknowledge the instructions and cautiously entered the now active portal, disappearing inside it.

As she entered the place, she could see herself sideways, very much like a videogame character... wait, was she looking at herself in a third-person view, that did not made any sense! But that was the situation she found herself in, clumsily moving her limbs around to walk in such a strange perspective.
After a few minutes of walking and stumbling all over the place, she finally reached what appeared to be a village of some kind. She could see houses and buildings, all that were also visible on the inside from her strange perspective. It didn't take too long until a small mob of flat two-dimensional people approached her, handing her a small box and speaking something in a strange language before returning inside their buildings. The girl was a bit baffled from what happened, but carried the box back where she came from.
After some more time walking, jumping and flopping, she managed to return to the entrance point, quickly wobbling her way inside the portal to return.

But strangely for her, as soon as she saw the laboratory lights once again, she quickly lost her balanced and flopped down on the ground, her heavy suit actually pinning her down!
Extremely confused from what just happened, Mabel tried her best to get up again, but with no avail... it was just like her body felt strangely floppy and weak, all wobbly, almost like she was... flat?!
As some scientists came to aid her, they soon realized what just happened: despite returning to their third-dimension, Mabel's body was still flat! If weren't by a slightly pancake thickness, she could be easily mistaken for a 2D poster.
Slipping her out of the suit, the manager looked at the two scientists as they held the flattened young woman up, her body bending around like paper. Why didn't she returned back to normal after returning the place?! Was it a suit malfunction?
The manager was surely puzzled by the situation, but tried their best to calm down the apparently scared two-dimensional girl. After all, flattening accidents were not that uncommon to see where they lived, it was always easy to pop someone to normal with an air-pump.
And so they tried... and tried... and tried... but nothing, it appeared that nothing was able to make her body return back to normal! Even after being inflated by air, helium, and all kinds of gazous composts, her body always deflated back into her flat state.

Poor Mabel was losing hope on her co-workers from not seeing any progress by her fellow scientists to restore her back, was she now fated to be like this forever?! The manager promised to make some of their researchers to work to find a solution for her situation, but for now it seems that she would have to stay like that for a while...
The now paper girl as some friends called her now, was starting to get used to her situation. Admitidly it was much harder to work or even move around while you are basically a living cutout, but she was getting pretty good at it, even managing to do stuff that she couldn't do before like entering locked places by slipping under the door, or bending her now rubbery and malleable flat body to reach tight places. She even mailed herself inside a big envelope to save up on her vaction trip, maybe being literally flat for a while wouldn't be that bad... she would just have to endure her friends comparing her to the pancakes on the plate at breakfast.