I'll cut for those who haven't seen The Six Thatchers yet! I thought I wouldn't theorize...but I was wrong... :)
(1) Have any of you heard of the
Extended Mind Palace (EMP) Theory? It is basically the idea that everything in the show after Mary shot Sherlock and he's recovering in the hospital during His Last Vow takes place in Sherlock's mind alone (half of His Last Vow, all of The Abominable Bride, all of The Six Thatchers).
I'd read about the theory before but now it is even more appealing, explaining things like John's characterization, odd dreamlike-filming sequences, the Mary saga, and
all these things in The Six Thatchers. Anyway, I find it quite fun and appealing, so that is my working theory for now. Of course some people might find that solution disappointing, but I think if it's handled well, it could be amazing and mind-blowing!
Sherlock: "Now, Magnussen. Magnussen is like a shark--it’s the only way I can describe him. Have you ever been to the shark tank at the London Aquarium, John--stood up close to the glass? Those floating flat faces, those dead eyes…That’s what he is."
(2) The great
continuing TJLC theory, coupled in with Mary-is-working-for-Moriarty and Lady E being a Moriarty plant, which I also find immensely appealing.
(3) I've read wonderful theories where all the events of The Six Thatchers are just Sherlock recounting (and editing) them for Ella during his therapy session, which is why things seem overly dramatic.
I can't believe this thing has been out just a few days and everyone is working really hard to come up with some awesome theories!
EDIT: Someone very nicely compiled
all of these into one post!
EDIT2: Another superb
master theories post!