Disclaimer: I own no characters, just the plot.
John was going out on another date.
He came home from the surgery and headed straight up to his room to change out of his clothes and collect a fresh set, then down to the bathroom to shower and get ready. Sherlock was curled up on the sofa, his back to the room, but he didn't need to see John to know what the older man was doing. He knew every footfall, every sigh, every movement that his flatmate made as intimately as he knew his own heartbeat. He also knew the exact sounds of John preparing for a date with yet another silly female: John humming to himself, the sound of the shower (three minutes and forty-five seconds, just a quick wash since he had showered that morning), the tap of the razor on the side of the porcelain sink as he shaved, even the sounds of him dressing and tying his shoes (foot on top of the closed toilet lid as he did the laces on his nicer brown brogues).
Sherlock knew every sound, and he hated them all.
He hated what the sounds meant. He hated that John would be spending his time with someone who was not Sherlock, someone who possessed a far inferior intellect, who could never hope to know John even a fraction as well as Sherlock did. He hated that John would likely not be home that night; hated even worse that there was a chance that John would bring his date back here, and then there would be more sounds - sounds that would send Sherlock to his room, pulling a pillow over his ears so he didn't have to hear the flavor-of-the-month coax those delicious, wanton sounds out of John that only he, Sherlock, should ever be allowed to hear.
He hated himself for being a coward, the night of their first case.
If Sherlock hadn't been so quick to dismiss the doctor's fumbled attempt to proposition him when they were on the stakeout at Angelo's, maybe John wouldn't feel such a primal need to seek companionship elsewhere. Then again, John was pretty consistent in maintaining that he wasn't gay - but "not gay" didn't necessarily mean 100% straight, either. Sherlock knew that John cared about him, even though the younger man knew that he was one of the most unlovable people on the planet (he had a pretty generous sample size to prove that particular theory). And despite his efforts to quash those inconvenient feelings, he had grown to care for John as well, more than he ever thought would be possible for a sociopath like him. Now he remembered why he shoved those feelings so far down inside himself for so long: it hurt like hell when they weren't reciprocated.
John emerged from the bathroom. Sherlock heard his flatmate's - his friend's - footfalls through the kitchen and into the sitting room. He could smell the particular cologne John usually reserved for dates, layered over the more familiar scents of John's shampoo, body wash, deodorant, and a scent that was just John. The younger man sighed and curled up tighter on the sofa, pulling his blue dressing gown around his lanky frame. He heard John stop next to the sofa, start to say something, hesitate, start again.
"I'm off to meet Jeanette, don't wait up. And don't blow up the flat while I'm gone." Sherlock grumbled in reply, refusing to turn over. He was momentarily startled, though, when he felt John's hand on his shoulder, a brief comforting squeeze before the doctor let go and walked over to the coat rack. He heard John shrug into his Haversack jacket and open the sitting room door. "Call me if you need anything," John called over his shoulder, closing the door behind him.
Sherlock pulled his knees up to his chest. He swallowed against the tightness building in his throat, and the salty prickle in the corners of his eyes, shut tight to block out the world.
"I need you."