John was going to kill them. Not just Sherlock, but Lestrade and Mycroft too.
Seven months. That's how long they had gone without telling him. And he wouldn't have even found out then if it hadn't been for a mere stroke of random observation.
It had all started with Sherlock telling John that some of his methods of observation were learnable and not just some superpower that only eccentric borderline-sociopaths could use. From that day forward John became obsessed with noticing the little things – an obsession that only lasted about week thanks to one particular incident. After four days of incorrectly deducing Mrs. Hudson, John decided to try out his not-so-skillful skill on possibly the worst potential candidate he could have ever picked – Mycroft Holmes. The elder Holmes had shown up unexpectedly in the sitting room of their flat in order to try to coerce Sherlock into taking a case about a dead Swedish spy.
The first thing that the doctor noticed was that the elder Holmes had gotten a haircut. Well, that was obvious; it barely even counted as an observation. After five minutes of intense scrutiny, the second thing he noticed was that Mycroft was wearing a silver ring on his left hand. No, John thought, not silver; platinum. Mycroft had more than a little money, and there was no way he would settle for silver, even if it was only a decoy ring. That's what his original gold ring had been, a decoy – hence it's tendency to migrate from right hand to left.
When John had originally asked Sherlock about it, the detective had laughed scathingly and said that it was most assuredly not a wedding ring. It was a decoy that Mycroft wore all the time in case he got called in on business unexpectedly. He would switch it to his left hand if he was going into a negotiation where it would be more beneficial to present himself as an understanding family man. Now, however, that ring had been replaced by a simple platinum one, the smooth surface of which was disrupted only by one intricate swirl.
In what Sherlock would later tell him was the biggest blunder any intelligent observer could make, John discarded the sight of the new ring as inconsequential. Maybe Mycroft had just gotten tired of the old one… after twenty-two years of wearing it.
John still hadn't given up on making a decent deduction when Lestrade called them to a crime scene two days later. The grey sky was spitting icy drops of rain on London as the doctor leaned idly against a police car, having been sent away from the body by Sherlock for quote, 'an inability to think quietly.'
"Here," the rather soggy DI said, holding out a cup of coffee to John.
"Thanks. Sent you away too, did he?"
"Yeah. Apparently, 'my erroneous conclusions are annoying,'" he said sarcastically, changing his voice to mimic Sherlock. Lestrade reached up the hand not currently holding coffee to scratch his nose, and that's when John saw it: A platinum band resting exactly where his gold wedding ring had been before his divorce three years ago. It was identical to Mycroft's, right down to the small spiral etched onto it.
"You know, that's the second time I've seen someone wearing that ring this week."
"Really?" asked Greg looking surprised. "I was under the impression that it was one of a kind. Well, two of a kind, but you get the point."
As a matter of fact, John sincerely did not get the point, but he said anyhow, "Yeah. Sherlock's brother Mycroft was wearing one too."
Just as Sherlock walked up to the two of them, the DI blinked rapidly and stared blankly the younger doctor. "You're joking, right?"
"Why would I be joking?"
Forehead knitting together, Lestrade pointed a finger at John and gave Sherlock a rather perplexed look. "Bit slow on the uptake isn't he? I mean, it's only natural that the rings would match. Really, it's not that much different from a normal marriage."
John's eyebrows disappeared under his soaked fringe at the word 'marriage'.
An expression of exasperation mixed with bemusement crossed the DI's face. "You didn't tell him did you?"
"Tell me? Tell me what, Sherlock? What did you forget to say?"
"I would have thought that it was obvious even to the most unskilled of observers. I didn't think there was any need for me to state the obvious," said the consulting detective, looking unconcerned.
"Okay, somebody, anybody, please tell me, who is married?"
Greg sighed exasperatedly. "John, your idiotic genius of a flatmate forgot to say that I got remarried in April." John knew what was coming even before the words left the older man's mouth. "And, well, it was to his brother. Here, look." He held out his left hand to show the ring to the other man, and sure enough, upon closer inspection it was clear that what John had taken for a decorative spiral was actually a cursive L and H looped together.
Rounding on his friend, the doctor hissed, "Exactly why did you not bother to tell me Mycroft and Greg got married? Or even that they were dating, for that matter."
"Do listen, John. I've already told you: I didn't think it was necessary. "
"Even before the wedding they'd been showing clear signs of being romantically involved for well over a year. Even you, John, couldn't fail to miss it. The mixed scent of their colognes." Sherlock looked between the other two expectantly. "Lestrade consistently showing up seven minutes earlier for work because Mycroft's flat is closer to a Tube station than his own. Mycroft inventing reasons to show up at crime scenes. And let's not forget the Detective Inspector's sudden fondness for wearing scarves in the middle of summer."
"It was that obvious?" Lestrade inquired, rubbing the back of his neck awkwardly.
"Painfully so. There are just some things about my brother that I prefer not to think about."
DI broke into a mischievous grin.
John threw his hands into the air. "I give up! This whole observation thing is a lost cause if I can't even tell that your brother and Lestrade have been married for over half a year."
Sherlock smirked. "It could be worse, John. Look at it this way: You could be the one who can't help but know exactly what his brother was up to the night before – or in a couple cases twenty minutes before - you see him."
The intense blush that covered Gregory Lestrade's face was clearly visible even in the dull light of the overcast sky.