The Devil’s Foot & The Dying Detective
So, I’m wondering. It’s very likely that Sherlock actually is ill in ep. 2. He seems to be affected by an infection or a poison that is causing halluzinations and a lot of pain in the terminal stage.
In ACD canon the devil’s foot plant is used to also poison people by burning the plant. The toxins have a fast impact on the brain, so that people go mad first, until they die. (And we have clues that they might do Devil’s Foot in ep 3, although they are not that blunt as for ep 2.)
To me it seems a bit repetitious, if they’d have these similar “cases” in two episodes. So what, if Sherlock’s illness is not resolved in ep 2? He might recover, but we don’t know what caused his condition. Culverton Smith will be set up as the baddie, but for Sherlock’s illness he’s the false lead.
What if Sherlock almost dies in ep. 2, because he had been poisoned with “devil’s foot”? The devil’s foot being some random foreign plant might of course be too easy for Mofftiss. So I’d suggest, maybe there was a very distinctive reason they set up Moriarty and Mary as the devil in TAB. Maybe this is another version of Mary shooting Sherlock literally, and killing him metaphorically by marrying John. So Mary/Moriarty pull their next trick to hurt and defeat Sherlock. On the meta level this will probably be something that separates Sherlock more from John. And on the text level we will see Sherlock get ill and almonst die. And in ep 3 we (and John and Sherlock) will find out, that it actually was Mary/Moriarty who poisoned Sherlock in the first place.