The smell was revolting. The bodies hadn't been found for nearly two weeks, in a small office in an un-air-conditioned warehouse in the height of the worst heat wave London had seen in years. What had once been a rather handsome trio of paid escorts (two male, one female) was now reduced to mostly liquids and three soggy skeletons. The stench of decay was apparent even from the parking lot, but inside the warehouse it was inescapable.

John wasn't immune. Despite his medical training, despite his time in the army, he had a rather violent physiological reaction to the smell just the same as Lestrade, Donovan, Anderson, and the other unfortunates assigned to the scene. Someone had thoughtfully set up a box full of plastic bags just outside the warehouse door, with a rubbish bin conveniently located just around the corner. John dashed back out to the parking lot, chest heaving, and grabbed one of the bags from Sherlock's helpfully extended hand.

"Rather interesting case, John - more interesting than I anticipated," Sherlock observed calmly as John voided the contents of his stomach. "Did you notice the staining pattern around the woman's ankles?"

John spat the last remnants of vomit into the bag and glared at Sherlock. "How is it you're not puking up your lunch like the rest of us? Hell, Anderson even lost it, and he's been around plenty more bodies than I have."

"This is hardly the worst crime scene I've seen," Sherlock said.

"I'm not talking about the sight, I'm talking about the smell," John snapped. "Surely you noticed?"

Sherlock shrugged. "Obviously. But I don't vomit. Never have."

John blinked and stared at him. "Never?"

"Not that I can recall. Comes from having no gag reflex."

"But what happens when you're sick? Haven't you ever had food poisoning?"

"Twice, but I just suffered through it both times. Honestly, John, it's not that big a deal. Can we get back to the case, or are you going to vomit more?"

John tied off the neck of the bag and tossed it in the rubbish bin. "I - Christ, Sherlock. That's not normal, you know that?"

Sherlock shrugged again. "It's hardly the only reason I've been accused of being inhuman." His lips twisted into a smirk. "Besides, it has its uses."

John swallowed against another wave of - something - churning inside him. Surely he didn't mean - but no, this was Sherlock, and he'd do well to remember that. John took a deep breath (carefully through his mouth, not his nose), and nodded. "Right, then. Murder victims. What was it about ankles?"

The ride home in the cab was nearly as bad. John's nose had eventually acclimated to the smell (mostly) while at the scene, but then everyone seemed inclined to move to the far side of the parking lot to hear Sherlock's deductions. And when John and Sherlock climbed into the enclosed back seat of the taxi to go home, it became immediately obvious that 1) they both stank of decomposition, and 2) John's nose wasn't that acclimated after all. It wasn't just his imagination, either - the cabbie was very definitely giving them both a dirty look.

"I need a shower," John muttered.

"Try the soap in the left-hand cupboard over the sink," Sherlock suggested. "It's the most effective at removing biological contaminants."

John looked up. "Would have been nice to know that when I first moved in, you know - I could have been cleaning the fridge with it this whole time."

"Nonsense - it's really not the kind of thing you want near food."

"And yet you think it's safe for skin?"

Sherlock steepled his fingers under his chin. "Have you ever really thought about smells, John? Unlike sight and sound, smells actually have to degrade over time because perceiving them uses them up. In order for you to smell a decomposing body, there literally must be tiny bits of decomposing body floating around in the air and then you breathe them in through your nose and mouth until they meet your olfactory receptors and they become a part of you. You only smell like decomposition now because your skin and hair and clothes and respiratory system are coated in bits of the victims."

John fought another unpleasant lurch. "Christ, Sherlock, why would you say that? Fine, I'll use the damn soap. You need a shower too - I'll be fast."

One hour, two cups of tea, and a very long shower (with the special soap) later, John felt much more human. And he kept finding his train of thought going back to Sherlock's earlier comments about there being uses for not having a gag reflex. He desperately wanted to dismiss the comment as having nothing to do with anything - surely Sherlock would have come up with a dozen ways his lack of a gag reflex made him superior to mere mortals, and none of them would have had anything to do with sucking another man's cock. But John would be damned if he could think of a single other plus - now he had the image of Sherlock in his head, and it wasn't going away.

Sherlock looked downright elegant in his navy blue robe, sulking around the flat with his hair all wild and still damp. It wasn't making anything easier. John glowered at his laptop and prayed Sherlock wasn't in a deducing mood - it was one thing to be involuntarily fantasizing about your flatmate, but it was entirely another for that flatmate to know about it.

"You're stuck on it," Sherlock said suddenly.

John looked up, trying to keep the guilt off his face.

"My medical abnormality really bothers you that much? I had rather hoped you wouldn't feel the need to lecture me about it - I have had specialists investigate it in the past, you know. It's not some unattended symptom in need of analyzing."

John shook his head. "Sorry - I'm not lecturing. Just - disbelief, I guess."

Sherlock let out an exasperated huff. "Fine. A demonstration." He disappeared into the kitchen.

"No, please, you don't have to -"

Sherlock reappeared holding a wooden spoon - John vaguely remembered leaving it in the drying rack the night before. It was a largish one, close to the length of John's forearm and with a handle the diameter of his thumb.

"Observe." And Sherlock tilted his head back and practically dropped the spoon down his throat. He held it there for several seconds, then reached into his mouth to fish out the flat end and extract the length inch by inch.

John's trousers were suddenly too tight. Sherlock returned the spoon to the kitchen, dumping it in the sink for John to wash later, and came back to prop his weight on the arm of his chair. "I used to do that in front of Mycroft to make him gag," he admitted with the hint of a smile. "He can't stand the thought of it."

"Yeah, I -" John swallowed hard. "I can't imagine why." He knew he was turning red, could feel the heat climbing up his cheeks, but if he stood up now, Sherlock would obviously notice -

"You're not disgusted," Sherlock said slowly. He stood and wandered closer to where John was carefully holding his computer over his lap on the sofa. "I assumed you'd be bothered, but you're - oh." His gaze dipped to John's crotch and stayed here.

"Yes, well. I'm going upstairs. Goodnight, Sherlock." John stood, turning so Sherlock couldn't see, praying his erection wasn't as obvious as it felt.

"It's barely six."

"Goodnight, Sherlock." And John escaped up to his room.