John thought spending the day alone in the flat on his day off might be boring, so he decided to accompany Sherlock to Bart's and watch him do experiments. As it turned out, watching Sherlock do experiments was a thousand times more boring than being slumped in front of the telly or browsing mindlessly on the internet. For once, there were no explosions, poisonous vapors, or even a small fire to make things entertaining. Sherlock just spent most of his time staring into a microscope.
"I didn't realize your work today would be so dull," John remarked, sitting on a stool across from Sherlock and skimming a newspaper someone had left. "I ought to have stayed at home, I guess."
Sherlock glanced up at him and switched a slide. "It's only dull because you're over there, not seeing what I'm seeing."
"Somehow I don't think anything under that microscope is really terribly interesting."
"It is if you're not an idiot," Sherlock replied and looked back into the scope.
John opened his mouth to protest, but then closed it. He wasn't entirely sure Sherlock had just insulted him, maybe he was just making a statement. After all, John hadn't looked in the microscope and proclaimed what he saw boring. He'd just made a speculation without evidence.
He realized dismally he was starting to understand Sherlock-speak.
John went back to reading the paper, but couldn't find anything of much interest there. He started contemplating getting a cab back to the flat.
Sherlock got up. He walked over to a rack and grabbed a tube.
"This is infuriating," he said as he walked back and slid onto his stool again. "I can't get the reaction I want. I've tried several different agents. This'll be the fourth one." He sighed heavily and went about preparing another slide.
"Anything I can help with?" John asked.
Sherlock flashed him a look. John took that as a 'no,' and looked back down at his paper, trying not to take it personally.
Sherlock returned his attention back down the microscope, in the process making a soft, impatient sound. He shifted on his stool and then fell still.
A minute later he gave a soft gasp and John looked up again. He was smiling under the eyepiece lenses. "Ah!" he said triumphantly. "There we go. Just as I suspected. A bit slower than I thought, but it's happening."
John shook his head and went back to reading football scores.
Sherlock drew John's attention back when he shifted on the stool again, sliding forward a little, pressing his knees together. John found the movement odd. Sherlock wasn't usually so fidgety.
"A bit excited?" John asked. "It really must be thrilling under there."
Sherlock emitted a little snort. He braced his hands on the table in front of him and pushed his bottom back on the stool, knees still pressed together.
"Yes," Sherlock murmured to himself. "That's how I thought it…hm…very interesting." He grimaced faintly. "And now…oh goddamn it." He said the last bit in nearly a whisper.
"Things not reacting the way you hoped?" John asked.
Sherlock didn't answer. He was quiet and still a moment, then he moved on the stool again, pushing his hips forward in a sort of undulating movement. John furrowed his brow.
"Sherlock, are you all right?"
"Why would I not be all right?"
John frowned and sat back. "You're not usually so…wiggly, during your experiments. In fact, you're usually stone still."
Sherlock grimaced, more pronounced this time, and slid his bottom back on the stool again.
"Are you in pain?" John asked.
"Why would you ask such a stupid thing?" It was strange talking to him while his face was buried in a microscope.
"I'm a doctor. I know the physical manifestations of discomfort."
"I'm not in pain," he said imperiously. "Stop distracting me."
John continued watching him, somewhat concerned, a little annoyed. Sherlock was still for a few minutes, John suspected out of sheer will so he wouldn't question him, then he rocked impatiently from side to side, clenching one hand down on his thigh. John suddenly realized what was wrong.
"Sherlock, do you have to piss?"
"I said shut up!"
John smirked. "You do, don't you?"
"This is a very delicate experiment. I need to see what happens here. I've tried three times without success, I'm not going to miss this."
"You're doing the 'I have to pee' dance like a little kid," John chided him. "It's rather amusing."
John got the impression if Sherlock could look away from his precious experiment he would have scowled at him, a scowl dark enough to knock him off his stool. As it was, he just made an annoyed growling sound and kept at it.
John chuckled and tried reading his paper again. He couldn't help but watch Sherlock out of the corner of his eye, however. He was still squirming.
"Just go to the bathroom," John told him.
"I am not missing this."
"You can always run it again."
"It took four tries to get this. Stop being thick, John!"
John shook his head. Sherlock squirmed again, pressing his hand between his thighs and clenching them around it. It wasn't quite in his crotch yet, but John had a feeling if he were alone he would have been holding himself. Again, like a little kid.
"You're going to piss yourself," John said. He licked a finger and turned a page. "And I'm going to laugh about it."
Sherlock was quiet and still for a minute, hand still stuffed between his thighs, gaze firmly rooted in the microscope. Then he made a soft sound—a gentle, pained gasp escaping from slightly parted lips. The sound rushed right to John's groin and pooled hot there. He blushed, and was glad Sherlock couldn't see him. It wasn't exactly a proper reaction to one's flatmate about to piss himself because he was too stubborn to go to the bathroom.
John tried to ignore him, figuring it was his choice to act like an idiot. Sherlock squirmed again, and it seemed to exacerbate the anguish, because he made a low moaning sound behind tightly-pressed lips. He moved his hand up higher and pressed it deeply into his crotch.
John's blush grew hotter, seeming to paralyze his entire body. He told himself he didn't find Sherlock slowly losing control exciting, not at all. That was just preposterous.
"I should not have had that coffee," Sherlock said, sounding both pained and annoyed. "Even if it does make my brain work faster."
John just gave a grunt.
Sherlock then made another sound, a sound John had never heard come out of him before—he actually whimpered. He slid his hips forward, pushing his crotch against his palm, the movement so sharp he nearly fell off the stool. He was gripping the table with his other hand, so tight his pale knuckles were even whiter.
He whined out softly, desperately, "John."
The spike of lust which instantly made John's cock begin to stiffen startled him, and he quickly covered it up with anger. "Bloody hell, Sherlock!" he griped at him. "Just get up and go to the bathroom!"
"I can't," that desperation still clung to his voice, vulnerable and needy. "John, please."
"What the hell exactly do you expect me to do about it? I can't piss for you."
"Bring me a pan. A beaker, a jar. Anything."
John boggled at him for a moment. "You're actually going to piss in something instead of getting up and going to the bathroom?"
"John." His voice was sharp, urgent.
John didn't know how the hell he could be so easily influenced into something like this, but he got off his stool and looked around for something. Sherlock made a soft gasping sound and undulated against his hand. John found himself wondering, unbidden, how close he was to losing control, if he would shudder and blush when it happened, if it was already leaking out the tip of his cock and wetting his pants.
John grabbed an empty beaker and strode over to him. He realized, walking, his cock was getting even stiffer. Once again, he was glad Sherlock couldn't see him. He stopped next to him and held the beaker out awkwardly. "Um."
Sherlock reached blindly for it, grabbed it. "John, could you," his voice was breathy. "Oh." It turned panicky and he squeezed his thighs harder together. John couldn't help noticing his trousers were ridiculously tight. If he pissed it would go right through them.
"Can I what?" John asked.
"Get me out," he said urgently. "Oh fuck, it hurts so much I can't move."
"Now wait just a minute. I'm not going to—"
"John please!" Panic again, harsh and vital. "I'm literally a moment away from it happening. Do you really want to watch me wet myself like a child?"
John once again couldn't believe he could be coerced into something like this. With an agitated sigh he moved behind Sherlock, reached around, and started undoing his trousers. He had to keep his hips back so Sherlock wouldn't feel his—response. It was bad enough he was in this situation, never mind being excited by it.
"You'll have to open your legs a bit," John said close to his ear.
Sherlock eased his thighs open with a choked sound. He was trembling, John could feel it against his arm. It must have been excruciating, not to mention embarrassing. John finished swiftly undoing his trousers, trying not to jerk him too much.
"Oh God," Sherlock moaned. "Hurry, John."
John got his button and zipper open and with a deep breath, pushed his hand inside. He had pants on and John had to grip him and work him out past all the fabric. His groin was warm and humid, his prick thick and soft. He did feel a little wet, but it could have been just sweat. John slipped his thumb over the head and retracted his foreskin.
"Ease forward," John murmured, and pressed his other hand into the small of Sherlock's back, coaxing him toward the front of the stool. Sherlock already had the beaker in position. "There we are."
Sherlock groaned loudly as the sound of liquid hitting glass came from between his legs. John felt his cock jerk and twitch as he pissed out a hard, steady stream. Sherlock's sounds of pain gradually became ones of relief and pleasure. Only as the stream started to abate did John realize Sherlock's cock was starting to thicken and firm. He had to adjust the angle to compensate.
"Mmm," Sherlock murmured. "That feels so much better."
John waited until the last few trickles dropped into the beaker before clearing his throat. "Well this is incredibly awkward," he said.
"Not as awkward as your prick being hard," Sherlock said, dark amusement leaking back into his voice.
John didn't think he could blush any more, but he did. "Might say the same of you." He gave Sherlock's prick a little squeeze and then a shake. "All finished?"
"Unless you want to finish me, yes."
Sherlock pushed his hips forward, so he slid through John's hand. "Please?" he whispered.
"Oh my God."
"Is it really much worse than what you've just done?"
John meant to remove his hand, he really did. Instead it betrayed him and started stroking. Sherlock firmed up completely, and quickly, in his palm.
"Just a few strokes," Sherlock gasped out. "Doesn't take me much."
True to his word, less than a minute later he gave a guttural groan and jerked his hips forward, sliding through the now-slick ring of John's fingers. John felt his cock jerk and heard the faint plop and splash of his shots hitting the liquid already in the beaker. It was truly, horribly obscene, and John nearly came in his pants.
When he turned away to find something to clean his hand with, he heard Sherlock chuckle throatily and looked back, fully humiliated and unspeakably aroused. Sherlock had finally taken his gaze from the microscope and was looking at John, bright-eyed and smirking. And holding a container of his own urine and cum between his knees.
"I had the results ten minutes ago," Sherlock said. "You were actually the experiment. And I think it was successful."
John gaped at him.
"Should I observe the results?" Sherlock asked, sliding his gaze down to John's crotch.
"You bloody well better," John said. "Or I'm going to throttle you."