New Theory! Motives
Spoilers ahead (duh).
For this two year break from Sherlock, theories will be primarily circulating around Moriarty's not-suicide. I had written a post on whether Moriarty is dead prior to the air of series 3, which you probably should read if you're interested in the rest of this post.
The post discusses how 1) Sherlock closes his eyes when Moriarty shoots and 2) the gun is no longer in Moriarty's hand when he falls. Both of these factors could be entirely insignificant, but because we know he is actually alive they could be of importance.
Or is he alive? This idea originates from my dad, who said he'd be surprised if Moriarty is actually alive or if a different villain is choosing to take his identity for the simultaneous all-screens-in-the-UK broadcast. Not a bad idea, but then you wait until the end of the credits and you actually see Jim saying "Did you miss me?". So I think we can safely rule that out.
On John finding out that Moriarty is still alive, he asks whether Jim hadn't had "his brains blown out". This suggests that Moriarty's corpse was found on the roof and examined by someone. (It wasn't removed by one of his men, which would have been a possibility.) Faking a corpse isn't difficult, at least in Sherlock, and god knows Jim has the resources to do it. This doesn't change the fact that Jim was on the roof, however. He talked to Sherlock, pulled a gun, and...?
There is still one central problem here (apart from the fact that Jim survived shooting himself). Why would Sherlock and Jim fake deaths at each other? It is clear that Sherlock always had the upper hand, pretty obvious that Jim believed his being-stupid-act. Sherlock himself said that he hadn't anticipated Jim shooting himself (yes, he did tell that to Anderson along with a fake theory, but let's believe this one statement). Though, as Sherlock proceeded to point out, it (Jim's death wish) was fairly obvious given their encounter at the swimming pool. Sherlock planned everything along with Mycroft, it seems bizarre to me that they would miss so obvious a detail. For Sherlock to miss it, maybe, but Mycroft as well?
Let's properly theorise. Assume that yes, Sherlock had a hunch Moriarty would kill himself. Leaving apart the issue of how Jim managed it - let's just say he did - Sherlock let him and faked his death. Why? He wanted an excuse to go undercover, to dismantle Jim's network.
If you've been following you'll notice two problems: 1) Moriarty would see that Sherlock faked his death or be informed by his men and 2) Sherlock successfully managed to dismantle Jim's network, though how would that be possible if Jim were still alive? Jim would prevent that, incognito or in person.
BUT: Jim is very clever as well. What if he saw Sherlock fake-kill himself and let him dismantle the network for Sherlock to believe he had the upper hand? Convince Sherlock he'd done it, actually ended his whole era thoroughly? While Sherlock was taking apart the old one, the whole world believing Jim was dead, Jim simply built a new network.
This begs the question of why Jim didn't just keep his old network, it's a lot less hassle. Well, Jim knew Sherlock was clever and that his network was in danger anyway. Build a new one, make Sherlock believed he'd killed off any Moriarty-associated organisation/ neutralised any hench(wo)men, then come back dramatically. He's insane. He does that sort of stuff.
So basically, Moriarty knew all along Sherlock would fake his death, Sherlock knew Jim was going to kill himself. Jim doesn't, builds himself a new everything while Sherlock is off breaking up the old one. Sherlock made another big mistake.
And that's what I don't like about this theory: Sherlock made that mistake. After everything, he couldn't recognise a live man when he saw one. Yes, he closed his eyes in the exact moment the trigger was pulled, but afterwards he didn't check again or .... something. He just left Jim's body there and off he popped onto a big bouncy castle.
The remaining two difficulties? Obviously what I discussed in the paragraph above and that faking one's death in the manner Jim appears to have done is extremely difficult. I'd venture to call it impossible, but apparently it's just improbable. Yes, we've got motives, but still no explanation as to how. In fact, I'd have gone with my dad's assumption if we hadn't had that last shot. So you can see where this blog is going.
Or, of course, the next series will start with Moriarty narrating: "There were 13 possible scenarios once I arrived on the rooftop", we'll only find out three and none of them for certain.
