"Well, it's COMPLETELY DETESTABLE!" Sherlock threw himself on the sofa and curled into a ball.

"Sherlock, we don't actually want the criminal class to improve their productivity. It's considered, in general, to be a BAD thing."

"YOU'RE a bad thing!" Sherlock yelled nonsensically, then continued to sulk and John's jaw started to twitch. He looked at the ceiling, trying to lower his blood pressure before addressing the lump of blue silk dressing gown in front of him.

Actually...that gave him an idea.

John crossed to the sofa and reached for Sherlock's elbow. Sherlock stiffened minutely but allowed John to take his hand, his eyes broadcasting his alarm.

"What...what are you doing?" Sherlock squawked as John's clever fingers found the inside of Sherlock's wrist.

"Taking your resting heart rate."

Sherlock sat up abruptly. "What? Why? Why would you do that?"

"Don't worry about it, it's a doctor thing," John said calmly, lowering Sherlock's hand and patting his shoulder in a very patient-friendly manner.

Sherlock paused, clearly considering. "What are you going to do with it?"

"Hmm? Oh, nothing." Which was completely true, but Sherlock didn't need to know that and it would drive him completely barmy. Which served him right for doing it to other people.

Sherlock was clearly not appeased. "Are you running an experiment?" He seemed genuinely curious now, the previous sulk all but forgotten.

John ignored him and re-settled in his chair with the paper.

Sherlock waited an abnormally long time for John's reply. Well, abnormally long for him. When none was forthcoming, he asked, "Are you selling the information to someone?" He seemed almost excited by this possibility.

John said nothing, just looked at Sherlock over the edge of the paper and turned the page.

"Are you adding this to a file you have on me? No, why would you have a file on me. DO you have a file on me?"

John didn't even look up.

Sherlock scoffed. "You're probably not doing anything with it." He crossed his arms.

John raised his eyebrows, his eyes never leaving the paper. "Nope, nothing."

Sherlock flipped back onto the sofa, then changed his mind and went to kneel carefully on the floor beside John's chair. "Please?" he asked, in his sincere voice.

John was unmoved. "I don't know what you're talking about," he said, then went back to reading the paper.

Sherlock stood in a huff and stomped to the kitchen in a flurry of dressing gown. Moments later though he stood in the doorway, beaker in one hand and a thoughtful and slightly concerned look on his face.

"Is this something that flatmates normally know about each other?"

John craned his neck around to look at Sherlock. He seemed a little unsure of himself, like a small boy who didn't know the appropriate protocol for suitable flatmate behavior. John wondered how many times in his life Sherlock had felt exactly that way, and felt his heart break for him, just a little.

"No, of course not." He gave Sherlock what he hoped was an encouraging smile.

"Oh." He paused. "Friends?"

Now it was John's turn to be confused. "Pardon?"

"Is this something friends normally know about each other?"

"No..." John offered hesitantly. He hadn't wanted to hurt Sherlock's feelings, that was never his intent.

"Oh," Sherlock said quietly. He frowned slightly, and retreated to the kitchen, lost in thought but the beaker in his hand completely forgotten.

John watched him leave, a bit confused but glad that Sherlock didn't appear offended. A warm glow of affection for the crazy madman settled in his chest. He really was the most interesting person John had ever met, and he was a lucky bastard that he got to see the vulnerable side of this brilliant man. Sherlock didn't admit that he didn't know something to just anyone, and John felt proud and humbled at the same time.

Sherlock was...concerned. Because he didn't get perplexed and he certainly didn't feel baffled. Sherlock looked at the facts and removed the impossible, then the improbable. But the science of deduction was failing him, mostly because there was no science to this and it was completely illogical and ridiculously frustrating. He would have to rely on John's input, the way he always did in these matters.

"John?"

"Mmhm?"

"Are you comparing it to yours?"

John looked up from his laptop. "Sorry? Comparing what to mine?"

Sherlock tried not to be annoyed. "Resting heart rate."

John blinked. "Sherlock, that was days ago." At Sherlock's huff, he relented and said, "No, I'm not comparing, I don't even know mine."

"It's 65 beats per minute," Sherlock replied automatically, surprising himself. He hadn't realized he knew that, actually. He hadn't intended to retain it, but there it was. It was the same as the average resting heart rate of a healthy adult male. Completely ordinary, the way John was in so many things while being at the same time inexplicably extraordinary.

"O...kay. That's a bit scary." John turned his full attention to Sherlock, looking bemused. "And how do you know that?"

"Oh for God's sake." Sherlock retreated to the kitchen because he had deleted that bit, but it wouldn't do for John to know that.

Sherlock worked on the problem throughout the remainder of the week, and when Lestrade texted with a new case, he threw himself at it, as boring as it was. At least, it was boring at first. When he was at the crime scene for the second time in as many days barking at Anderson and saying things that made John get that little crease between his eyebrows, he decided that this was affecting The Work and that was unacceptable.

He needed to solve this, now. Ok...

It was an action with no functional basis as John hadn't yet and reportedly didn't intend to use the information for any normal purpose. Because the action was pointless, it must be sentimentally based. John had performed the action when Sherlock was feeling upset. Because it had stopped him from feeling upset, logically it must be tied to the intended sentiment.

Conclusion: This was a gesture from one person to another intending to relay comfort, good feeling, and general affection in times of stress.

Good. Fine. Solved.

He looked over at John, standing behind the police tape with his hands on his hips, glaring pointedly at Sherlock. Sherlock ignored whatever inane question Anderson had posed and walked closer to his friend. When John didn't move away, which of course he wouldn't because John didn't back down from anything, Sherlock removed the glove on his right hand. John watched him carefully, and Sherlock moved slowly, so John would know he meant it when he delivered this gesture.

He grasped John's wrist, his skin cool against Sherlock's warmed fingers. He pressed his first two fingers into the thin skin there, feeling the beat of John's heart, reaffirming that his friend was alive, and well, and real. John's look of confusion caused Sherlock to smile slightly, sure that his own face had looked the same when John had performed this act for his own benefit. He truly did appreciate this man who had come into his life and made everything just a little bit better. He knew he could be difficult and demanding and generally awful, but John stayed by his side through it all. And he couldn't be more grateful. He tried to let it show on his face, to tell John all the things he couldn't express the way most people did.

"What are you doing?" John asked.

"Taking your resting heart rate," Sherlock explained, willing him to deduce his meaning.

John's confusion melted into understanding, and then amusement. Then he looked at Sherlock, really looked, the way John did and the way Sherlock didn't. And John's eyes softened and then creased at the edges before he closed them and nodded, almost to himself.

"Alright," he said, softly. "Alright, go on. But go easy on them, yeah?"

Sherlock nodded seriously, then practically bounced back over to the crime scene, deductions already spiraling out of control in his mind.