Timeline

Once, there was a pair of twins that grew up in a far-off country. They did everything together, specializing in folk art and other things. What one twin lacked, the other made up for. They were rather close as brothers.
Then one day, one of the twins decided to try a completely new mode of artwork- Furniture making. The other agreed, and they set to work. One designed their first chair, the other assembled the pieces they acquired. The resulting piece was rather crude at best...
But what else could you expect from a chair made entirely out of human parts?
The twins considered this a success and merrily continued their horrid line of work, traveling the world and perfecting their craft over the years. At first, they created small pieces of furniture and accessories... But at some point, they wanted more creative liberty.
That is when they came to America and opened a small furniture shop. They sold fine furniture there, even normal looking pieces to pay for upkeep... But their finest work required sacrifices... People with unique imperfections who wouldn't be missed...

It just so happened that a young woman entered their shop one day. The lady found something unique about their work, and who were they to refuse her a peek? After all, she was alone... And the look on her face when she saw the macabre art was nothing short of ecstatic, one more quality they found fascinating...
However, as the doctor who was following her found the shop as well, she told him she had no need for any of this furniture... An insulting remark indeed, made worse by the doctor's probing touch. They warned the lady and the doctor of their specialties, and made it clear that they wished to make the lady her own piece of furniture...
And then the lady declared they were worthy of being judged.
They were fortunate the doctor stepped in with his own agenda. He explained that the lady, Cathy, was actually a cruel prison warden who would be more than happy to torture them behind bars. Then the doctor proposed an alternate fate: What if there was a place where they could practice their art without fear of retribution? A place where they could do what they wished to limbs and torsos? A place they truly belonged?
And so, Doctor Danny invited the twins to become Reverend Gray's angels.

Unfortunately, the Reverend dismissed the twins due to sensing a strong, unequal dependence between them. "I do not seek such incomplete beings," he said, "One or the other. The one who does something about his twisted dependence."
The reverend gave them some time to think about this and sent them home, telling them to come back when they had an answer. Of course, this made the twins rather upset; They both wanted to take part in the Reverend's project, but they couldn't understand what made them unequal. Perhaps the Reverend's words had an effect on them... Which one started this? Which one simply followed along?
Danny came to check up on them a few days later. They lamented their plight, asking him why it only had to be one. Danny's answer? "I guess that means you can't complete anything on your own?"
They took enough offense to collar him, but Cathy came to add salt to the wounds with a broken music box they clearly made. She claimed the joints were so weak it broke on its own, "Considering you two made it together, it's much more fragile than I thought."
They tried to defend themselves, saying their goods had never broken like that before, but Danny and Cathy's words continued to drive them mad. "Perhaps you two working together warped the joints." "I wonder which of you is the unskilled one?" "It was something made by two different people." "Aren't two bodies redundant?"
Danny and Cathy left the twins with those nagging thoughts in their minds. They decided to close up shop earlier than usual...
Then along came a different woman asking about the two that left. The twins explained the situation with her, but she merely agreed that Cathy was right. This drove them to snap at her, clinging to their younger memories and insisting that there is no one person involved.
The woman decided they were both incomplete. "How can imperfect humans create something perfect?" The woman muttered, "It's impossible, right?" Ergo, "Completion" must be self-contained...

That was the final straw. That night, long after the woman left, they had both made up their minds on how they wanted to solve their problem... But they took different paths to do so.
One brother was plotting something in the workshop. The other snuck up from behind and beheaded him while he was working.
The surviving twin walked into the church alone the next morning. This man, with markings on both sides of his face, introduced himself as "Shin," a complete man. He was accepted into the building shortly after.
He quickly began to close up shop, putting all his things in boxes and preparing to move to this new building. The woman from before dropped by, only to be told of Shin's new existence and bold plan. She muttered something before running off, and Danny walked in shortly after. Alone. Shin's suprised Cathy wasn't even part of the project and insists on inviting her to the murder building. Danny has other plans, though...
But in the end, Cathy was more than thrilled to join the fun.
At some point, a serial killer who tore out their victims' eyes made the headlines. Shin attended the meeting to discuss this, taking the time to plot out room designs in his sketchbook as he did. He pointed out that this person was not unlike the three of them- They take delight in grisly deeds most people would reject for various reasons.
Outside of that meeting, Shin wasn't too concerned with this eyeball thief. Danny took care of that fellow himself.

A few days later, after the mysterious killer has been dealt with, Danny and the Reverend visited Shin while he's hard at work on his floor. Shin was very happy with the lodgings in the basement, and while he intended to improve the area he's grateful he got to work on a dark, windowless floor where no outsiders could find him.
Unfortunately, as Danny and Gray had a pleasant conversation about the building, Shin realized he left his sketchbook in the church.
Fearing the loss of his motivation, he traced his steps to recover it as soon as possible. What he found in the chapel was a young boy sitting in the pews, flipping through his designs in the book. He snatched the book from the boy quickly enough... But the smile on the boy's face as he recognized what those drawings really were...
The boy, Eddie, just so happened to be the one who tends to the gravesite near the church. The boy was very suspicious of Shin's blueprints. In fact, as soon as the Reverend arrived at the church, he glared at Shin as he reported vandalism and signs of grave robbing in the churchyard. After the Reverend sends the upset boy home, Shin professes his innocence, claiming he would never do such a disgusting thing as dig up corpses.
So Gray sends him to keep watch over the graveyard that night. As curious as he is, Shin wonders why he was sent as lookout of all people.
All of a sudden, Shin is ambushed by a masked child with a shovel. He easily recognizes the child as Eddie, who flat out accuses him of desecrating the graves. He won't believe Shin's denials, but Shin... Shin realizes that a normal child would not watch over the graves at night and try to murder trespassers. He's personally impressed by the skill the boy put into the gravestones, and expresses his desire to talk artistry with him.
Eddie's not interested. Plus, he's still wary of Shin. So the artist uses his connection with the reverend to lead the boy to the basement of that building...

Down a long staircase, through a secret door disguised as a stained window, Shin leads Eddie to the room where the reverend is meeting with Danny and Cathy. He explains the situation as he introduces the boy to the others, with mixed results. (Really, Cathy? A Halloween costume?) Danny is fast to scold him for bringing an outsider in.
But Eddie is no mere outsider. He knows the smell of death, and this secret society only furthers his suspicions of Shin being the one who keeps wrecking his graves...
Completely fed up with being blamed for a crime he would never commit, Shin collars the boy and drags him to his floor to see the furniture.
Eddie's amazed by the quality of Shin's work. The artist explains he puts a great deal of time and effort into capturing the emotions of his victims in the furniture they become. Plus, he points out how none of the materials used smell like they come out of the ground. He prefers to use fresh material, not looted corpses.
At last, Eddie begrudgingly relents. The poor child just wants to know who is responsible for ruining the graves he put so much time and effort into crafting. To further prove his innocence, Shin offers to join him in watching over the graves to catch the robber. Besides, he's curious as well... And perhaps Shin could talk art later?
Turns out Eddie's still not interested. Oh well.

At some point in the night, as Eddie and Shin are watching from a stakeout nearby, the true culprit saunters into the graveyard with a shovel. The pair watch with horror as this disgusting brute of a man digs up a woman's grave and yanks her corpse from her coffin. As disgusted as they are, Shin and Eddie follow the graverobber to his hideout...
For the sake of the reader's sanity, what the graverobber was doing with the corpse will not be explained in detail, but it involved careless manhandling, sloppy butchering, and slobbering all over the limbs.
Shin was absolutely revolted by this reckless display, and Eddie was traumatized by how he was treating such a beautiful woman resting in the ground. No punishment they could enact on their own would be enough to bring justice to that monster, so Shin suggests they work together to make the man's final agonizing moments a true work of art...

LShin and Eddie rope the other floor masters into their project. Everyone, even the skeptical Danny, got to put their respective talents to use and torment the rotten graverobber. Daniel and Shin has a little chat in the middle of it; Danny asked why Shin needs to show off in a place no one can see him. Shin asked why Danny fusses over the details if they've been given a place to showcase their talents, since Shin believes seeking nothing but peace and safety won't help anyone in the end.
Eddie ran in after coralling the grave robber where Shin needed. The boy took a moment to apologize again for accusing Shin for graverobbing, but Shin merely brushes it off. He was more interested in working with Eddie to complete the "finishing touches" and even encourages the boy a bit.
After the gruesome show ended with the grave robber being thrown into a giant grave and slaughtered, Eddie admits he had a fun time despite not trusting most of the adults. Shin invites Eddie to visit him anytime. Thus began the odd friendship of a disturbed young gravekeeper and an equally disturbed artist.
The experiment was almost complete. There was an "angel" on every floor except for the very bottom... And Floor B6.
This experiment was not for the faint of heart. For a good while, Gray had a hard time finding someone suitable for B6. Some canidates were left broken and empty. Others lashed out at the other floor masters. Many met their end at the hands of the other floor masters when they retaliated.
Maybe the problem was Gray seeking someone less intelligent for B6? Whatever the reason, Shin was left to tend to the remains. Any body that didn't pique his interest was handed over to Eddie for burial. This went on for a while...

When Deborah passed through Shin's floor, he noticed her suprise at his elaborate artwork. But she cared not for his work nor did she want to hear details on the individual pieces. "Humans are nothing more than humans," she said, "We are all damned alike!" Shin was highly offended by this, seeing no beauty in those who don't appreciate art or diversity.
The other floor masters noticed similar traits about Deborah when they met for debriefing. Danny found her to be a bold, calculating woman who was so sure devils and angels were the same. Cathy admired her dominating demeanor and good judge of character, but found she overlooked herself in her judgements. Maybe that's why Gregory murdered her when they reunited on B2.

Gregory expressed a desire to kill whenever he liked, so Gray temporarily assigned him to B6 as an experimental subject. When Daniel expressed his objections, Gray reminded everyone of their place. The angels were merely there to carry out their roles. The building went into full operation from then on.
Unfortunately for everyone, Gregory was not suited for B6 at all. Not only was he sloppy, but he eventually grew bored of killing and didn't even bother to put his victims out of their misery. The other floor masters did not appreciate the sudden influx of mangled sacrifices, especially not Shin. His motivation began to sink...

Without the inspiration for his work, Shin fell into despair. He began to isolate himself, and wouldn't even let Eddie into his workshop for a visit. It got worse after Gregory started murdering people again and stripping them of all their belongings.
One fateful day, Eddie decided to check on his friend Shin. The boy found the artist slumped over his worktable in despair. Despite the materials getting better, Shin miserably laments he was unable to find new inspiration for his work. Never in his life has he found all his materials faded and pale. He even asks himself if he's finally lost his passion for creating art.
Eddie cries that Shin's suffering because he can't create. That means he's still engaged, right?
Then Eddie promised to take over Shin's floor if he can't go on. This cheers Shin up enough to try focusing on his work...
As he sat there, desperately wondering how he could possibly achieve this completion he seeked from his work, he cut his own finger off by mistake.

Most people would start screaming for a doctor at this point, but what Shin got from looking at his severed finger were distant memories of his lost brother and inspiration. He was consumed with the desire to create something out of this, to incorporate his flesh and bone into his work.
So he did. Shin chopped off his own limbs and put them back together, destroying his body in a mad frenzy to make himself into the most beautiful piece of furniture... Before he finally bled out from his injuries and died.
He left behind a mirror, a mangled corpse and a floor full of grotesque furniture. Eddie was allowed to replace him as master of B4 and buried all of Shin's hard work in graves. Under the belief that everything he buried was his, Eddie kept the rest of the building's corpses from then on.