A quirk of the dynamic John-Sherlock-Mycroft that I particularly appreciate toying with in my rewrite, is that they play out like a game of Rock-Paper-Scissor.
The story of John and Sherlock, fundamentally, is about the relationship between the two men. They ADORE one another. But, at least at first, John doesn't really see Sherlock as... Well, human. An equal. Sherlock doesn't, either, but in the other direction. John has this first impression of Sherlock as a great genius, nearly a God amongst men. He's above feelings, above mistakes. He could fix just about any problem if he so-chose. Now, with that said, one could argue that John should therefore hold Holmes to a higher standard of behaviour, but to John, living with this tall child is a necessary cost of watching the God up close. That all fades away, with time. Sherlock begins seeing him as his equal (more than past S3 imo) instead of his little pet to do his bidding, pretty quickly in fact, but John takes a bit more time to stop worshipping Sherlock. I don't think he ever truly does. Sherlock is just so sharp, John feels his very purpose was to write about it. Socrates and Plato. The Scissors and the Paper.
Now Sherlock, on the other hand, worships only his own mind, or so he would like us to believe. And since the narrative is from John's perspective in most iterations, we tend to fall for it, at least at first. Then, inevitably, Mycroft is introduced. A man so smart Sherlock feels like a fool in comparison. And not just any fool, either. Mycroft is stern, calm, cold, and calculated. He's all that Sherlock could be, if it weren't for those damn emotions of his! But Mycroft is above all that. Mycroft is perfect. Mycroft. Is. God. You've heard of little siblings idolizing their elders, but that's to a whole other level with the Holmes brothers. Sherlock cannot even look at Mycroft without feeling like Lucifer, cast out of Heaven, replaced by this perfect angel beyond his own comprehension. It drives him mad, he just wants to cut him where it hurts, bring him down a notch, but it's pointless. Mycroft is too solid. He takes it all without as much as a glare. The Scissors and the Rock.
That's all well and good, you might say, this little cycle of worship and awe and "how can you be human", but it seems we've reached the end. Mycroft doesn't respect anyone's intelligence as much as his own, and CERTAINLY doesn't worship anyone!... Except... Think about it. All his life, or rather, Sherlock's, Mycroft has had but one goal (especially true in my version); to protect his little brother. From the rest of the world, certes, but mostly from himself. Deep down, Mycroft knows Sherlock is brilliant, perhaps even close to on par with him. But he lacks any sense of self-preservation or impulse control, whatsoever. Do you KNOW how terrifying it is, to care for a genius child with volatile emotions and no fear of God? Mycroft had to put it in him, he just had no choice, you see. Sure, getting his little brother to view him as an all-powerful, all-seeing, all-controlling figure might not have been the best move for their relationship. But Mycroft would sacrifice anything for Sherlock's safety, even his image in the mind of he who matters most. So you can imagine how FRUSTRATING Sherlock's insistence at risking his life for a daily thrill can get! And don't get Mycroft started on his eating habits, or his drug usage, and God damn does he even sleep enough– Until he meets John. Until Sherlock meets John, that is. And suddenly, his little brother is four, five, six months sober. For the first time since he began using. And suddenly, Sherlock isn't taking as many risks when working his little puzzles, doesn't want harm to come to Watson, so he says. And suddenly, Sherlock looks healthier, happier... Safer. After a lifetime of seeking this outcome, Mycroft still hadn't achieved it. And this man, this doctor, this... John managed the impossible in a matter of weeks. How could Mycroft NOT worship him, a little? He doesn't always agree with his approach, of course. He finds John too soft on Sherlock, too pliable. A mind so sharp requires cold, hard discipline! And yet, Sherlock always opts to obey John instead of his brother. And eventually, so does Mycroft. Sure, he still tries to argue from time to time, but in the end, when it comes to taking care of Sherlock, what John says goes. And anyone who knows anything about Mycroft knows just how divine that is. The Paper beats Rock.
For those of you wondering where Lestrade fits in all this, I guess he'd be like, a hammer? The main difference to me between Mystrade and Johnlock, is that Lestrade doesn't start out worshiping Mycroft, quiiiite the opposite. So the hammer breaks rock, can also rip the paper, but I suppose the scissors can... Cut... The handle?? I don't know. Lestrade is weird. He really shifts the dynamic between those three, because he admires Sherlock as much as John does, but he also sees him as just a kid, kind of like Mycroft does. And then Mycroft is impressed Greg got so much respect from the other two, and is a bit jelly if we're honest, but like... He doesn't exactly fear him the way he low-key fears John (especially after S2E4, in my version. God I can't wait to publish this shit!). And John is simultaneously like "whoa, you knew him before, and he actually listens to you (because John doesn't even realize the power he holds)?" and like "damn, you knew him before, and in all that time you didn't recognize how transcendantly amazing he is? Smh 🙄". And those are two very contradicting positions.
I think it shows Greg is one of the characters I changed the most for this. That's because he's way more important to the overarching plot, and he actually ~has an arc~, so.