What was going through Sherlock's mind during TLD?

 (Sherlock meta by Ivy Blossom)

Q: [...] I was just curious as to what you think was going through Sherlock's mind during TLD. How do you think he understood John deserting him? Like, why do you think Sherlock never seems to doubt John, or lose faith, as John himself did? What must he have thought of John to assume or calculate that John would seriously hurt him? Why would he think that? And yet, how did he still imagine John could or would return? Was he always actually able to predict John all along, or....

A: I’m not sure it’s clear that Sherlock was planning for John to seriously hurt him in The Lying Detective; his plan doesn’t require that. Sherlock doesn’t end up in Culverton Smith’s hospital room because of John’s violence. He’s there because he’s drugged himself to within weeks of his own demise.

That said, I don’t think Sherlock is especially surprised that John hit him. John has a well-known tendency towards violence, particularly when coupled with strong emotions he can’t process. When that incident occurs, John is already sideways coping with the sudden death of his wife by blaming Sherlock and pushing him away, so I don’t think it’s a huge deductive leap for Sherlock to suspect that some level of violence against him might ensue.

When John hits Sherlock in The Lying Detective, it isn’t even the first time John’s deliberately hurt Sherlock: Sherlock incited him to it in A Scandal in Belgravia, and John hit him in anger multiple times at the beginning of The Empty Hearse. Sherlock has every reason to expect a violent reaction from John, but to be honest I don’t think he was factoring it in as part of his over all plan in The Lying Detective. It wasn’t required.

It’s interesting to consider the premise of your question: what do you think Sherlock never doubts? That if he needs John enough, John will definitely be there to save him?

I’m not sure Sherlock is convinced of that. While John is riddled with self-loathing through The Lying Detective, I think Sherlock is, too. The Norbury reference tells us that Sherlock considers Mary’s death to be his greatest failure and miscalculation. He clearly believes that he deserves to be blamed for it.

It’s not clear to me that Sherlock is so confident that John will run to his side. But he’s prepared to pull out all the stops anyway. The plan isn’t for John to save Sherlock; Sherlock is trying to save John.

I think Sherlock is very much aware that he might fail in that task, and that if he does, it will probably cost him his life. He is in the middle of this potential suicide mission even while telling Eurus-as-Faith that suicide isn’t an option. Sherlock has decided to save John, or die. His very last plan, his own death recorded via the device in John’s cane, wouldn’t have saved him. It would only have been evidence to solve his last case.

When Culverton Smith is about to kill him, Sherlock says he doesn’t want to die, and he means it. He can only mean it in that moment because he thinks it’s imminent. He isn’t expecting John to break through the door, is he? Does that mean he lost faith in John?

Sherlock’s constructed crisis wasn’t a test of John’s heroism, which is frankly never in question. When Sherlock looks at Culverton Smith and realizes there’s no way out, it’s not John who failed. It’s Sherlock’s rescue mission that failed.

Could Sherlock predict all of John’s actions? He knows John very well, and he can predict many of his choices. But not all of them, as he admits. Sherlock thinks he’s about to die, but John makes a choice Sherlock didn’t count on: he saves Sherlock in spite of everything.