Will comment in the next few hours.
ETA: whoops, didn't realize how late it was. Should be a review here by sometime tomorrow.
ETA II: actually, this ended up being shorter than I thought. Here are my thoughts:
The emails from Dr. Fitts seem… too polite and too long for a repeated inquiry related to workplace safety? I personally feel like a busy doctor wouldn't bother with unnecessary "smalltalk" in the emails; stuff like "Boy, winter is here! We had that cold snap just before last weekend, and now there's more snow expected by Friday." and "This weather just won't give us a break, huh?" is just extra text that distracts from the important pieces of the email. I feel like typically most doctors wouldn't bother writing out entirely new messages, they'd just reply to the email chain with something like "just checking up on the status of the request per below email". Why is the doctor so familiar with the custodian at the start? Why does he only ever email the same custodian and not go to more higher-ups? I feel like there needs to be more scene-setting so the reader can better get a feel for what's happening. I saw that the emails went from "Jerry" to using a surname, but that was just across 3 emails of relatively similar content. Maybe have some other emails of usual maintenance duties be introduced first to set up both the doctor and the custodian characters?
Similarly the email from Senior Researcher Dr. Bellis is kind of shaky. It stands out a lot as super official jargon-dense and almost suspiciously verbose, so by the time the first ending of "the dude wrote something that just sounded official" reveal is dropped, I as a reader don't feel too surprised because I thought it was excessively official already. Now I know that it was that way because it wasn't particularly legit, and it feels like it was kind of predictable? Also, Bellis and Fitts's writing kind of sounds the same in the last two emails, so maybe change up the writing styles so that they sound like more different characters.
The endings I'm a little torn on. On one hand, I think it makes sense to have multiple endings because "what if there were actually different offshoot dimensions"? But on the other hand, that's a hell of a coincidence, especially if it's unexplained. Personally I feel like you should have multiple endings because the tale is bland otherwise, but what's missing to tie the separate parts together is a reason behind the sudden anomalous manifestation.
Although I will say, as a doctor, why didn't Fitts just put some sandpaper on his shoes or walk more carefully on the ice?
I wouldn't upvote this, but I wouldn't downvote it either. It's clever, but incomplete. I personally don't have any ideas for a reason for the manifestation though.