This is one that has been bugging me for a while now.
Why did Sherlock’s memories of Eurus only begin to resurface, after all these years, around the same time that John just happened to be having an affair with his sister? Before then, Sherlock’s memories of Redbeard are always triggered by Mycroft, Magnussen or during his near death experience.
But what triggers Sherlock’s flashback in TST when Mary drugs him? Ella later tells us this is a recurring dream but, as far as the audience is aware, this is the first time Sherlock experiences this particular memory on the beach, with ‘Redbeard’ and Eurus’ song in the background.
In TLD it makes sense that Sherlock has this flashback when he collapses on the bridge because, unbeknownst to him, his sister is there with him and this is the first time he’s seen her in decades. Adding to that what he tells John later about the drugs opening up ‘doors in his brain’ he couldn’t access before.
So, again, what is it about Mary that ties into Eurus and Sherlock’s past? How convenient is it that this recurring dream only starts in this series when Eurus decides to begin the final stage of her plan and messing around with John? Sherlock knew nothing about John’s affair until the end of TLD.
It just seems like another missed opportunity to tie Big Bad Eurus with Mary who, again, could have been such an awesome villain and would have given us more reason to care about the finale because she was someone we had already grown to know and understand - not just a random cray cray secret family member thrown in at the last minute. How mind blowing would it have been to find out Eurus ‘programmed’ Mary to fake her death, knowing it would cause a rift between Sherlock and John and send her brother on a path to destruction that would have pleased Mary enough to give her life also (as this is apparently what she did with Jim as well). Or, better yet, have Mary’s death had been faked and something they planned together.
Just...anything other than Eurus being the cliche she was and Mary being made into a saint with all her previous flaws being forgotten.
