Okay, guys, apparently the absence of grammar-clue guessers this round has created a vacuum into which I am being resentfully drawn...I didn't mean to do this! I just noticed that "BOX ONE" was an all-caps title and decided to very quickly skim through the participating authors' AO3 profiles to see if there was someone who always wrote their titles in all-caps because that would have been an easy signpost (for the record, none of the participating authors I could find on AO3 do regularly use all-caps titles, so that's a bust). But, while skimming past people's AO3 pages, I UNWILLINGLY noticed a few tics that scfrankles and starfishstar have apparently conditioned me to double-take over, and so I regret to inform you that I have a few grammar-and-tag-based Rational guesses:

Happyeverafter72 has written Coules fic before, uses the tag "Cuddling & Snuggling" for many of their works, and deploys a very distinctive two-line run of short dashes to indicate scene breaks, so I'd say "The Case of the Missing Marrow" belongs to them :)

Disheveledcurls tends to write Elementary fic titles all in lowercase and specifies where the fic falls within the show's canon timeline in between [brackets] in their summaries. Therefore "all the way" can be traced to their doorstep!

Yuliares uses an html quote indentation in all their summaries. "Weathered til Content," j'accuse!

*collapses onto my fainting couch, urging the disgruntled grammatical spirit of absent detectives to move along to someone else in this seance*