Were you following the SH Spesh setlock when it got really spoilery?
No, I mean that, there's a point -- circa 30-Jan-15 as well as later -- when that happened. It's possible these were done to fake us out. But they looked like rather major plot spoilers.
Final Problem discussed this item at length here.
And cupidford has a visual compare/contrast to FP's post.
Before setlock, BTW... this always happens. :D
This is a mix of s3 and s4 speculation about our missing villain from s3; if you read the post, you'll see why I say "missing" because of what little we know. Marked for s4 because reasons.
FP also has a nice detailed set of speculation posts about CAM's mind palace.
Returning to s3 (via Three Patch Podcast) about markers and the bonfire. Reactions and insights after seeing Hearse.
"Why is she like that?" about the updated Mary.
A brilliant interpretation of Sherlock (using what he learned from Irene in SiB) in HLV. And, for that matter, what Moffat learned.
Equally brilliant, unknownsister's Sherlock, Circles, and a Second Childhood.
A waltz for Sherlock: On Things Gained and Lost in The Sign of Three from AO3.
For more meta and speculation, check out Three Patch Podcast's Recreational Meta master post.