In A Strange Land by MrsEvadneCake (Stranger Things, 180K, all characters + canon pairings + very light Steve/Nancy/Jonathan)
It was written between seasons 2 & 3, so it doesn't take S3 canon into account and basically functions as an alternate season 3. And man, does the writer ever nail the horror vibe of the first two seasons. It's not particularly gory, but parts of it are definitely straight-up horror in the Stephen King mold; it's excellent mood reading for this time of year. I loved how well the cast was handled - all the characters get their own moments to shine, even minor ones like Mr. Clarke and Kali's bunch and Dr. Owens, there are excellent feels for The Party and Steve/Nancy/Jonathan (mostly gen, but with vague hints at the pairing), and the character voices are really well done. It's one of those stories that you can sink into, especially at a time of year when the horror vibe is particularly welcome.
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