Sherlock Series 4: 8 Huge Predictions (And Why They Need To Happen)
5. Mycroft Is Dying
As mentioned previously, the writers of Sherlock love to hint at things to come, making subsequent rewatches all the more rewarding. One way this might currently be happening is by setting up Mycroft's death. For a start, Sherlock and Mycroft have a lengthy discussion in The Abominable Bride about the imminent inevitability of Mycroft's death. Since all that took place in Sherlock's head, is it possible he's subconsciously thinking about something we don't know?
That might seem a bit of a stretch, but back in the present Mycroft seems much more affectionate than usual, asking Sherlock to promise him he won't do any more drugs and specifically requesting that Watson looks after him (when he's gone?). It's curious that among everyone in Sherlock's mind palace, Mycroft is the only one depicted as hideously, life-threateningly unhealthy.
It would be great to see this happen because it'd force some tangible, weighty character development on Sherlock, who in his stoic, closed-off state seems impenetrable to change. Sherlock's lack of affection at times makes him seem non-human, but if there's anyone (perhaps other than Watson) who could evoke actual emotion, it's Mycroft.