Some examples I've encountered recently include Dr. Cimmerian's video on the logistical challenges posed by the real-life rarity of death row inmates, and a D-class created by DrChandra who has served his time with the Foundation, been released and is now working at a Foundation front company. (Tyrone also appears in SCP-4525.)
I've been writing some tales myself lately which focus on the early adulthood of an extremely villainous person. My solution for making him somebody readers want to root for was to surround him with other, antagonistic villains who are even worse.
I think that's a strategy you're approaching in another way here. Sybil has murdered people, but she regrets what she did and chose that solution as a way to stop other people from hurting her. Compared to a lot of characters we meet at the Foundation (hello there, Dr. Bright!) that's sympathetic as heck. The other experiments done with this door have been with people whose crimes were less sympathetic or more heinous, relatively speaking. And looming over all this is the Foundation, which is still morally grey at best. Choosing to essentially torture and kill people to learn about anomalies and keep them contained — even if the people are criminals, even though it is necessary to protect the universe from danger — may, in some ways, be less sympathetic than Sybil's crime.
Word count on the draft in its current state is a little over 4600 words, which is on the long side for a tale. Other authors I've done tale crit swaps with have given me the impression that shorter tales, in the below-4000 area, tend to be a bit more approachable for readers. (This one just about made me cry in around 1100.) But there's no hard and fast rule! There are tales by authors I like which are over 9000 and got enough upvotes to stick around. (Vend-a-friend may be of interest: its tales are long, relevant to your topic and have very dark themes.) It's your judgement call on what message you want to get across and how much space you want to do it in.
I bring this up because from a narrative standpoint, you've got a clear and straightforward progression of events. Sybil is in her cell —> takes a look at the documentation —> gets brought to the test chamber —> enters the anomaly —> freaks out and gets chased by Amber —> hears a sympathetic researcher on the com —> gathers her courage and has a personal revelation that helps her push back against Amber's memory —> makes her way towards the exit.
I think given that progression, you may be able to cut down on length significantly and still tell the full story you want to convey. Each of these events and turning points gives the reader a peek into Sybil's inner experiences, and through her, a look at the anomaly and the Foundation from her perspective of being trapped inside of both. It's super easy as an author to digress and describe cool and interesting stuff we have in our headcanons. But in revising, it helps to be a little ruthless and trim out everything except what the reader will need to orient themselves to the world of the characters within a tale.
Here are a few specific things which stood out to me:
You wouldn’t want your test monkeys getting too relaxed. And that’s exactly what she was to the Foundation.
Second sentence can go, IMO. First sentence already did the job admirably and ends the paragraph on a nicely bitter note.
The designation ‘D-5785’ wasn’t some arbitrary number, it marked her as expendable, a liability, and at best, a useful data point on a graph. She had been informed many times however, that her stay here has been far more useful than the other D class personnel that the Foundation kept.
Some run-on sentences there, and I noticed more throughout the draft. A free Grammarly account can help with catching stuff like that so you know what needs to be polished! My own method is to just obsessively re-read my drafts a gazillion times, which has its perks but is kinda labor intensive. >_>
But in her time here she has only dealt with seemingly safe things.
There are several places where you seem to switch back and forth between past tense (she had dealt) and present tense (she has dealt). Whichever one you decide to go with, it's gotta be consistent.
This section has some great description and characterization otherwise. When you're referencing other SCPs which are articles on the wiki, I would recommend cross-linking them. A lot of readers (myself included) first really got hooked on SCP by following up crosslinks. In particular if you can think of recent (say, series IV and V) SCPs that fit in well with your story, that can be a great way to entertain your readers while also giving a shoutout to other authors whose work you enjoy.
I feel like there's a little too much of the SCP article written out in the text. I would want to see the header properly formatted and the article excerpts quoted, like so:
Item #: SCP-5001
Object Class: Safe (provisional)
Special Containment Procedures: SCP-5001 is to kept in storage room-5001. Storage room 5001 is to be equipped with a single standard door frame, six standard issue Phillips head screws, an electric screwdriver, and three spare hinges.
That way you can reduce the SCP article excerpts, while interspersing them with Sybil's thoughts in a way that feels natural. I'd also recommend against including a specific SCP object number since eventually there will be an article written with that number. (Obvs if you write the door AS an SCP successfully you can just link it at that point!)
As for how the door functions - previous D-class were able to bring material items out of the anomaly with them and the items in some way pertained to the guilt it reified for them? That's interesting. I'd like to see that used in Sybil's case as well, sort of a tangible take-away for the lesson she learned from her time there.
I dig what's going on with the interior of the anomaly and the creepiness of getting chased by Amber's ghost (or possibly fake ghost, who knows). I wish there were a few more details about what exactly Amber did to Sybil; the lack of that reveal blunted my sympathy for Sybil.
I think the Foundation researcher is a little too sympathetic. Even if they care about her on a personal level, they're still going to do their best to keep it professional, keep her focused and moving and getting them data. As far as the Foundation and the reader are aware, this anomaly doesn't kill people. Every test subject so far has gotten out. So it's not a rescue since she's likely not in any real danger.
The ending feels unfinished to me, to be honest. Amber confronting Sybil with her guilt is good as far as it goes. "Yeah, I was a bully, but you resorted to murder and you deserve to feel guilty about that forever" is a good catalyst for a personal revelation, but the revelation itself never fully arrives. We see Sybil being forced to confront her own choices and recognizing that they were wrong. But personally I want some kind of "eureka" moment here. I want Sybil to make the leap from acknowledging her guilt to realizing there is a better way for her to handle being bullied and put down. Whatever that new motivation turns out to be, maybe she resolves to stick to that and try to be a better person in the future. That's the kind of character development that gets me reaching for the upvote button!