Voyeurism
It had happened so many times before. He shouldn't have expected anything different than what happens from the other times. It's just it had never happened with anyone but John, which was why he kept holding out hope that the next time would be different. He wouldn't get undeniably hard beneath his pants and trousers every time he saw his flatmate and friend undressing, half-naked, or only wrapped in a bath robe after a bath. He would always hope he wouldn't get hard from seeing John this way, but always expected it.
Unable to bring himself to take care of his erection, Sherlock would ignore it until it went down. Taking care of it meant diverting blood from his brain to his cock to feed his more primal need. And that meant distracting himself from the Work. He couldn't have that. he also couldn't have John walking around in nothing but his pants and a robe while he was trying to work. That was even more distracting.
But what could he do? he couldn't very well tell the man to put some clothes on. That would not only be suspicious, but stupid because the man lived here, for Christ's sake. John would look at him funny or… even worse, figure out why Sherlock needed John to cover himself. So Sherlock bore the torture on the days John would venture out of his room in only trousers or pants and a robe.
It wasn't easy, but Sherlock was always able to hide the… excitement in his pants by staying where he was, either on the couch thinking or in the kitchen working on an experiment. Sometimes, though, the detective had to go to his room to hide from the other man, lest he figure out that Sherlock did indeed have human tendencies and needs every now and then.
He never took care of it tough.
One day, Sherlock heard some commotion from upstairs, coming from John's bedroom. He went up as quietly as he could, creeping up each step like a cat stalking its prey, until he reached the man's door. He was just about to knock and ask if everything was alright when he heard John moan a bit too loudly. Heat immediately spread from Sherlock's face to his groin at the wonderful sound and he swallowed thickly.
John was masturbating.
And the more Sherlock thought about it, John touching himself, moaning every time he passed his hand over the head of his dick, and the sound of skin lightly slapping skin, made Sherlock as hard as ever. He ran downstairs and slammed the door to his room shut once he was safely inside. His breathing was ragged and uneven, his cock was swelling with arousal, and his whole body felt hot. This had to stop.
That was when an idea forced its way into Sherlock's mind. Obviously, he would need to relieve himself in a few days if things continued like this, but the thought of just having a wank without seeing John made his stomach tie itself into knots. He needed to see John while he did it. While they both did it. And so, Sherlock had a plan.
The camera hadn't been expensive at all, given the detective's salary. It was small, easy to use, and high quality. Perfect for watching a certain someone while they got themselves off. Setting up the camera in the perfect spot hadn't been hard either. John had gone to Tesco's to get some food for the two and Sherlock saw his chance. The moment John had left, Sherlock rushed upstairs and into John's room, placing the camera in his already picked out spot, and had left, without a trace.
When John had gotten back, he went up to his room, as Sherlock had predicted, and started to wank himself off. The camera was already recording to Sherlock's laptop while the man was working on an experiment, trying to not think too much about John and his hands touching himself. His thoughts all became too much, though, when he could begin to hear John through the thin walls of the flat.
Abruptly, Sherlock stood from his seat, grabbed his laptop, and went into his room to watch John get off with himself. He sat on the bed, his laptop in front of him, and opened the device to see John very roughly, and very quickly, moving his hand up and down on hid member. Sherlock decided to watch from the beginning while the rest of the footage was being recorded as John continued his wank.
Sherlock watched intensely as the beginning of the recording showed John first palming himself through his trousers, eyes closed his concentration. He did this for a while before unzipping his pants, and holding himself firmly in his hand, free of the fabric restriction. Sherlock felt heat rising in his stomach and face, his own member becoming even harder than earlier.
John began to move his hand up and down the shaft of his cock as he reached into the bedside table for something… oh. Lubricant. Of course. He stopped his movements with his hand and squirted some of the oil onto his palm, beginning to pump with renewed vigor as the lubricant did its job to make the member easier to pump.
Suddenly all of this was too much for Sherlock. He could feel his member, hot and throbbing in his trousers, begging to be freed. He groaned in frustration, paused the video, and got comfortable in his bed as he unzipped his own trousers and pulled them off. His erection was more visible now that the dark material of his trousers weren't obscuring it, though it still wasn't exactly out yet. The sleuth played the video as he began to palm himself through his restricting pants.
