As the days passed by, we 3 were left alone in the dark, i was the second one to wake, the first was special case 2, the girl, called herself Regina never uttered her last name though, its not like i cared, once i was awake.....but this is still 4 days before i woke-up, Regina was the first of us to wake-up from her metamorphosis. She broke out of it early because her body was much more adept at absorbing radiation, than us. When Regina came to, the first thing she noticed was suffocation...
The radiation on level 13 was so thick and heavy, it was suffocating us. Of course anybody that would end up here in such a state, would end up overloading, and start to experience uncontrolled mutations, so for anyone who was going through metamorphosis was being rebuilt from scratch, and when the person was complete again, they would come out of their said figurative cocoon, as a MET short for METAMORPHOSED. 

People who went through this process were held at the Facility to make sure they didn't lose control of their powers while they were out in public. Because the world didn't know about MET's, people had a clue, but nobody knew for sure, only the ones who went through it knew, of each other's existence. Now since the world didn't know about the MET's, letting them roam free was, 1st dangerous, 2nd problematic for the UNCC-United Nations Concealment Council, created in the background to control situations related to MET's. the organization isn't really publicly known and only works with and for MET's, and then 3rd stupid people would try to get it from wrong sources causing even more casualties.

Now let me give you a reality check, not every person who is hit with this radiation makes it out alive, there's only a 23% success rate to metamorphosis, the rest either die the moment they are hit with the wave or die a slow agonizing death as the radiation rips their body apart from inside and out, in only the remaining people, does the radiation start to circulate, which grants the person the ability to subconsciously battle the radiation itself in their dreams, which causes the comatose state, now the success rate to this metamorphosis is even lower than before. Now? it's only about 12% out of all the 23% that made it to the metamorphosis stage, but couldn't win the battle in their minds and at some point they stop breathing, drawing their last breath in a battle against a monsterous radiation wave of an unknown origin.

The 12% that make it through are able to live with the radiation, because their bodies have adapted to the radiations mutation. Some still have the ability to control their abilities like a sixth thumb or an extra sense, but for those who cannot, the Facility has developed a bracelet similar to an ankle monitor but worn around their wrists, which keeps their radiation leak in check, while dispersing of any excess that might collect around or on them.
Now that that's cleared, hyper concentration of radiation can choke or kill even the strongest ones among the METAMORPHOSED, so when Regina experienced it, she naturally panicked and blew up almost half of level 13, out of pure panic.
Now remember, us special 3 have absorbed the most amount of radiation energy on the accident site, and were also left on level 13, so our emotions have become a trigger for our radiations release and cause.

So when Regina found herself in a dense cloud of radiation, being choked by the very air she breathed, in a place she didn't know and what she had gone through.... all she knew or remembered was the explosion from the cafeteria she was in during work hours.
Her clothes had been changed, by the sight it looked like a hospital gown, with no sense of time or day, being stuck to an IV in a room that looked desolate, and nearly destroyed, laying in the dark, her panic brought out her metamorphosis' ability.
Regina was a simple secluded girl, in her 20's, content with her own company, choosing to exclude herself from social events, and generally just preferring to stay out of sight.
Now the reason i'm telling you about her life before the accident is because her personality and decisions are what shaped her metamorphosed abilities, granting her control over the shadows...
I know, what your thinking according to that logic, every other shut-in should have the ability to control the shadows. But it's the decisions we have made our whole life are what mold us into the kind of person we are, and since each person has different decision making methods, each person develops different versions of the same ability, but just as each person is different in their own rights, so are their abilities, affecting the matter surrounding them in just as unique ways.....

Which is why Regina, a secluded person who prefered to hide and disappear, rather than face her problems got the ability to control the shadows, an ability which allowed her to move silently, disappear in plain sight, and exist in her own little space, providing her with the solitude she always wished for, but that very desire also caused her abilities to grow in potential, imagination became her limit, and the shadows became her friends, her subconscious mind's desire for true friends gave the shadows surrounding her sentience regina felt people lacked. 
Having such an ability comes with the price of your mind's ability to discern between reality and thought, since all your thoughts related to your ability would be realised by the surrounding radiation. This sometimes cause the users to lose their touch with reality itself, causing harm not just to themselves but to everyone surrounding them.
Regina' were specially potent because of 3 primary reasons, first being the concentration of radiation we were left in, second was her kindness, no matter how wronged she was, no matter how much the world beat her down, she always reacted with kindness, not holding grudges....making her abilities her first shield and her unwanted sword, and the third reason was her fear, fear is one of the strongest and oldest emotions our kind knows, it is primal, we learn to fear everything before anything else, even happiness comes after curiosity, which is triggered after we push through the crippling fear as an infant, it was this very fear regina always kept with her through childhood, through puberty, and even now, the fear never left her, her mind found comfort in this fear, which, yes crippled her and yet allowed her to move from one spot to another, it was this nature of accepting fear into herself, which caused her abilities to grow exponentially, to the point where they started to slip out of her mind, even when she wasn't conscious.

All of these factors made her one of the most potent shadow manipulator known to humankind.
Her shadows didn't just encapsulate her to give her solace but plunged the world around her into darkness even broad daylight, her shadows were so thick and potent they blocked every ounce of light from within the space they occupied.
Trapping everyone who would be stressing her, and in this moment it was this whole place, that was making her stressed and so her sentient shadows decided to consume every being with a beating heart.