You know…
When John first meets Sherlock, Mycroft wants John to take a salary for keeping him in the loop about what Sherlock is up to. Nothing you’d be uncomfortable with, right? Possibly mostly to do with his drug habits? I presume that Mycroft didn’t imagine that a flatmate would ever commit himself so completely to Sherlock that he would, I don’t know, cancel dates to keep an eye on him, or blow off major plans to merely be available to him on a danger night.
We always sort of saw John’s refusal as a means by which John demonstrates his commitment to Sherlock, his loyalty to him.
Is it a betrayal that John calls Mycroft when he finds Sherlock in a crack house? Rather than taking responsibility for Sherlock himself and keeping his secrets? Is it a sign of John’s increasing distance from Sherlock that he involved Mycroft at all at this point?
Just curious.
I don’t think so. The “danger night” scene from Scandal was a clear indicator that John and Mycroft (and Mrs. Hudson!) were united in their efforts to keep Sherlock off the drugs. The reference to “a danger night,” the fact that John says they checked “all the usual places,” everything about that scene says they were policing Sherlock’s behavior in a way they’ve done previously. When John calls Mycroft in Vow, I see it as another link in that chain of events.
Mycroft asking John to spy in Pink is of a totally different character. John didn’t even know who Mycroft WAS at that point. He was just a creepy stranger asking John to spy on his new flatmate for money. Even laying the issue of loyalty aside, the whole thing was pretty gross. Now if John would have known Mycroft was Sherlock’s brother, he still would have said no, I believe- because it’s not Mycroft being aware of what Sherlock is up to, but the sneakiness of going behind Sherlock’s back secretly, that John objects to.
When John calls Mycroft in Vow, it’s not a secret report or a scheme hatched behind Sherlock’s back. I doubt John would cooperate if Mycroft wanted to help spirit Sherlock away to rehab against his will, say. I see at as John simply enlisting an ally with an equally strong concern for Sherlock’s safety to confront him about his drug use. To my mind, the fact that when the confrontation turns into an issue about a case (rather than the drugs) John immediately sides with Sherlock, disproves the suggestions of either disloyalty or increasing distance. It’s only with the drugs that John can’t trust Sherlock to do what’s in his own (or anyone else’s) best interests.
It occurred to me yesterday that from John’s perspective, Mycroft is basically the brother-in-law.
They don’t always get along, but when it comes to Sherlock’s welfare, they’re both more or less on the same side. And when it comes to Sherlock and his own welfare, sometimes you really need reinforcements.