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Sherlock Holmes is, without argument, a genius of deduction.
This has the unfortunate side effect, however, of making the man an absolute arse, a trait that comes out, well, always, but particularly around John.
“You prefer Skippy brand,” the detective points out when they are shopping. Don’t ask why John seemed to think that bringing the know-it-all along was a good idea. At the time, he’d thought that teaching Sherlock how to shop might make him actually do it at some point.
It was not worth it.
“No, I don’t.”
“Yes, you do. You eat Skippy at a rate of one jar per every week and a half. You eat the store brand at a rate of one jar every two weeks. You are simply claiming otherwise because I haven’t had a paying case in a while and the store brand is cheaper.” Sherlock grinned smugly, never having glanced up from his phone.
For a brief moment, John has a rather intense fantasy about taking that phone and dropping it down the men’s room toilet after throwing it against a wall.
“Wait a—you’ve been studying my peanut butter intake? What possible purpose could that have?” John demanded. Sherlock just shrugged and then brightened.
“Case, John!”
“But the—“
“Oh, never mind the shopping, this is more fun! Besides, Mrs.Hudson will do it tomorrow if she sees it empty. Come on, John!”
And then they were off. Long story short, the case led to a tattoo as a lead, and Sherlock decided to go check it out while John went to his “boring” job.
When John got back, Sherlock was sporting a nice shiner on his right eye and, naturally, hadn’t iced it. Swearing softly, John grabbed some frozen peas—Mrs.Hudson had, true to Sherlock’s prediction, gone shopping—and tossed them at the detective, who put them on the swelling area without a word.
“So?” John began after a significant pause.
“Hm? What?” Sherlock asked, looking over from his thinking position.
“Who punched you?” The words were drawn out and slow.
“Oh. Tattoo shop owner. Didn’t take kindly to my deduction that his license is expired. Obvious, really, even if it was forged.” John snorted.
“Well, there’s your mistake. Did you get the information?” Sherlock, although he would never admit it, sulked, crossing his arms and dropping the peas in the process.
“No. They threw me out. Literally. Idiots,” he huffed, and John laughed.
“Come on, get your coat. I know a place we can go. He’s an expert, and he and I go pretty far back.”
John knew a tattoo artist. That was…unexpected. Sherlock flitted through all that he knew about John, from his favorite type of peanut butter to his worst triggers, and nothing indicated that the otherwise clean-cut army doctor would associate with a tattoo artist.
Secondary school friend? No, the furthest back John’s acquaintances went was medical school, and the only evidence of that appeared to be Stamford. Medical school drop out? No, John Watson would not remain friends with someone who dropped out of university to become a tattoo artist. Would not have had time to.
Perhaps a military friend, retired to tattooing? Entirely possible, and by far the most likely outcome, given what Sherlock knew of John Watson.
Sherlock was satisfied with his reasoning until they arrived at the shop. A swift glance revealed that this man was not former military in the least. His tattoos were at least a decade old, and they violated the uniform code, showing over his hands and neck. His posture was all wrong, too, without even a hint of discipline. Thin, slouched, heavily tattooed, black dyed hair that curled just under his sharp jaw—no indication of how he knew John Watson at all. Sherlock frowned in frustration, tapping his fingers against his thigh and wishing he had a cigarette.
“Well, I’ll be damned. John Watson,” the man said, grinning and getting up to embrace John. The doctor grinned and briefly clasped the man’s forearm. A greeting common among friends, but eliminating former lovers. That would have been a hug, at the least. So truly just a friend. But how?
“Riley. Good to see you,” John said, smiling as they broke away. “Good to see you’re still in business. Not that I’m surprised, of course.” Why wouldn’t he be? Business go out all the time, why would John be shocked if this one did?
“Better not, Watson, after all the work I did on you. How’s it holding up?” What.
“Pretty well. Little bit of damage, but nothing too bad.” What.
“Oh, I can patch that up for you. Does your friend want to get tatted too?” Tatted.
“Sherlock? Oh, no. Actually, we’re here because of an investigation…”
“Oh, right. I’ve been following your blog, although not as closely as I’d like. What can I do for you?”
John glanced at Sherlock, but the detective was staring off, lost in his Mind Palace as he flipped frantically through everything he knew about his flatmate. John Hamish Watson had a tattoo. Clean cut Army doctor no more.
“Sherlock?” John asked, waving a hand in front of Sherlock’s staring eyes. “O-kay. Um, here, Riley. Do you recognize the work?”
“Is he okay?”
“Yeah, he just sort of…does this sometimes,” John tried to explain before sighing. “He’s fine. The, uh, tattoo?”
“Right. Yeah, this is Daniel’s work. See this line? Definitely his.” John nodded and thanked him before shoving Sherlock out. Sherlock came out of his Mind Palace, having stored the conversation. He took out his phone and texted the solution to Lestrade, having realized that the tattoo artist would have killed the person, before turning to John.
“You have a tattoo,” he said, eyes narrowed. John had a tattoo. John had a tattoo and Sherlock did not know about it. That was unacceptable; Sherlock must know everything about John.
“Yes, I do,” John said, still walking. “Solve the case?”
“Yes, boring. I want to see it.”
“See my tattoo?” John asked, struggling to catch up.
“Yes.”
“…No.” Sherlock did a double take, deductions flying through his head.
“Self-respect aside, you wouldn’t get a...tramp stamp. You're a soldier, and a doctor, it wouldn't be socially acceptable in those circles. I would have noticed regardless, given the style of shirt you wear and how often you bend over. I have seen your calves, most of your arms, and a good portion of your chest—no need to look so shocked, you often wear a robe. Therefore, the only areas I haven’t seen are your upper thighs, groin, and back. You wouldn’t get a tattoo that close to your groin, although your hip is a possibility. Your back is most likely, considering the amount of area available. So, which was it?”
John took a deep breath, clenching and unclenching his left hand. “Sherlock. You have catalogued my favorite type of peanut butter, the exact temperature of my bath water, the average length of my showers, and I’m nearly positive that you have taken samples of my, well, everything. For once in your life, leave this one thing to me.” Sherlock frowned.
“But—“
“No, Sherlock. Leave it.” Unacceptable. John had a tattoo that Sherlock was not aware of, and that was unacceptable. Sherlock had to catalogue everything about John Watson, it was nearly a biological imperative for him. Still, biding his time had worked well in this endeavor in the past. He could do it again.
A week had passed, and all Sherlock had figured out was that the tattoo was certainly on the back, thanks to a “mistaken” grab of John’s trousers that showed no hint of ink on the hip, and was likely touching the left shoulder, going by the comment about damage. But that was all. Un-ac-ceptable.
Finally, Sherlock instituted step one of his plan—upping the heat in the flat.
“Sherlock, why is it so hot in here?” John demanded, coming back from work and pulling of his jacket and his jumper just to reveal a thin, short sleeve, white shirt under it. Not see-through, unfortunately. Sherlock grimaced.
“Heating’s broken. Mrs.Hudson is working on it,” Sherlock sighed, checking an item off of his mental checklist.
Step two: strip poker.
John should not be that good at cards. Sherlock ended up in his boxers before John had shed more than a sock—and the detective had dressed in all his layers.
Never. Again.
Step three: spilling items on John’s shirts while keeping the heat up.
“Augh! God dammit, Sherlock, it’s five in the afternoon, why do you even have coffee? And why is it that hot?” John demanded after Sherlock spilled coffee.
Honestly, the detective wasn’t even subtle about it; just walked over to John with a full thermos of boiling coffee and dumped it on him with a monotone, insincere apology. He wasn’t even trying.
To his intense frustration, John just got up and walked all the way to his room to change. With a despairing moan, Sherlock flopped to the mattress dramatically.
Step four: emotional manipulation begging.
When John came downstairs, Sherlock had put on his best begging face. “John, for the love of my sanity, please just remove your shirt.” John sighed.
“Why does it even matter, Sherlock? You know everything else about me, why is this one thing so bloody important to you?” John demanded, and Sherlock shot off the sofa.
“Everything is important! You are John Watson, the only person in my entire life who is so entirely important as to have a whole, undeletable room in my Mind Palace filled with what I would usually consider mere trivia! Because I have made it my mission to know just as much about you as I know about tobacco ash, if not more, and yet there is a permanent mark on you that I have not catalogued and noted and learned about. That there is a part of you that is not as intimately familiar to me as my own self is abhorrent to me, because you are John Watson and more important to me than my own breath!”
Silence, charged by the most passionate words that Sherlock had spoken in their acquaintance, stretched between them for a long moment before John sighed.
“Well, damn, what can I say to that?” he muttered, pulling off his shirt. The first thing to catch Sherlock’s eye was the puckered entry wound on John’s left shoulder, until John turned around.
The most violent sight on the back was the exit wound, spreading out in a star pattern, but then Sherlock’s eyes were drawn to the ink after that. Stretching from the edge of John’s scar, slightly ruined by the wound, to his other shoulder in a small arch, were the words “All Measures” in dark black ink. On his right shoulder, small but bright, was the RAMC symbol.
“All measures,” Sherlock murmured, fingers tracing gently over the words, memorizing the texture of them on John’s skin, the way they sank through his epidermis and into his dermis.
“Yes. It’s from the Hippocratic Oath—“
“Ah. ‘I will apply, for the benefit of the sick, all measures which are required,’” Sherlock murmured, and John blinked in surprise.
“How did you—“
“It had to do with you, of course I memorized it,” Sherlock muttered, tracing the RAMC symbol when he’d finished memorizing the words. “Naturally. Before you deployed?”
“Day before my first deployment. Reminds me that all measures can include killing those that threaten my patients,” John affirmed quietly. “Carried me through a lot.” Sherlock nodded, pulling away at long last.
“Thank you, John.” John nodded, not pulling his shirt back on as he sat there.
“Did you mean what you said? About how important I was?”
“Of course I did, John, I don’t say things to you that I don’t mean. Well, not things like that,” Sherlock said, pulling away to go over to his lab. John smiled and walked over, setting one hand on Sherlock’s shoulder and squeezing lightly.
“You’re the most important person in my life too, Sherlock, of course you are,” John said. More words pressed at their lips, but for now, that was enough.