Because I couldn't resist.
It wasn't the first time Sherlock had experimented on John, and it definitely wouldn't be the last, even if it was perhaps the most disastrous experiment he'd performed.
There wasn't much reason for drugging John other than boredom, though it would've been easy to make excuses. Sherlock could've gotten away with calling it research for a future case before Reichenbach. Before everything between the two flat mates was obliterated, never to truly heal ever again.
Perhaps that was the motivation, Sherlock idly mused as he observed John drinking the tea he'd prepared for him. Other than a slight grimace and a baleful glance at the detective, the doctor showed little hesitation to down the scalding beverage. Perhaps...
Foolish, foolish doctor. Rather than collapse as expected fifteen minutes after ingestion, John blinked blearily at the detective and mumbled incoherently.
After identifying the rumblings as jumbled, meaningless speech, Sherlock returned to his website, where he idly began documenting the drug's effects on unsuspecting veterans. There was little disturbance within the flat, save John's fluctuations in mumblings and awkward bumbling, where the doctor crashed into various pieces of furniture without stopping. He'd bump into the couch, glare at it, and stumble into the table or their chairs seconds later. John bounced between chairs with little chance of injury, and Sherlock didn't remove himself from the kitchen table to help his flat mate.
This continued for thirty minutes, where the detective's eyes remained locked either on the doctor or his laptop; either way, John was the subject of his intense studying. He could stare at John as much as possible without questioning, without the doctor's uncomfortable, dissuading cough or comment, without Mary's enigmatic grin, infused with triumph or happiness, he never knew which.
John would've known. John knew. John saw, understood, was fluent in social niceties and complexities, yet he ignored Sherlock's discomfort and attentions in favor of desperately lavishing the wrong fiancé with his smoldering emotions.
"Bloody hell," John muttered as he scrutinized the skull atop the mantle, glaring balefully into the empty, apathetic sockets, foreheads inches apart. "What did you do to make him talk to you?"
Sherlock's pulse raced, and he fought for composure as he strode into the living room.
"You're just a skull," the doctor slurred, "an empty skull. I'm not an empty skull; I've got a brain."
Albeit muddled, Sherlock mentally supplemented. He stood beside his leather chair, scrutinizing the doctor, contemplating the consequences of directly interacting with a drugged John.
John's rumblings fell into incoherency once more, and he pushed himself away from the skull.
There was a gait the doctor lapsed into when he was upset, one that straightened his figure and, depending on his irritation levels, livened his steps with a slight swagger. It was a strut Sherlock took great pleasure in eliciting, however subtle it may have been.
The detective's favorite gait hadn't broadcasted John's emotions so poignantly before, and it far surpassed his previous struts. John, clearly upset, would've been far more obvious in his irritation were he not drugged; perhaps the average human would've been able to see it. The drugs enhanced the strut, John's body emphatically and painfully swinging like a pendulum, and, though he crashed into furniture with nearly every step, he continued his journey determinedly, as though the fate of the world rested on his ability to convey his emotions through action alone.
Sherlock would've let the peacock's strutting continue, if he wasn't heading straight for the chemical-ridden kitchen table.
"John, watch out." Sherlock rushed forward, John ignoring him, and gently grasped his shoulders, forcing the doctor to halt.
"Sherrrrl," John grumbled, leaning backwards into the detective. "I drank funny tea. You always make crappy tea."
"Do I?"
"You do," John giggled. "Is'kay, though; I don't mind. I'm the cooking one, and you're the deduction one."
"You forgot the blogging."
"To hell with the blogging! It's all words, words, words, and you don't like it. Always criticizing me." John pried himself from Sherlock's grasp and faced the detective. Sherlock shuffled backwards in an attempt to put distance between his racing heart and John's flushed, drugged face.
John, however, had other ideas. His hands latched onto Sherlock's, firmly tugging him forward.
"Always criticizing me; always leaving." John's breath ghosted over Sherlock's skin, embittered by drugs and black tea.
"You're one to talk. What about Mary?"
"I love my fiancé. She helped me... When you were dead. You, you broke me. She's helped me, a little. Enough to make a difference."
Sherlock's eyes stung; he'd been foolish to assume that John would've understood, would've fully forgiven him. "You still don't understand."
"I understand that the person I loved the most abandoned me through a fake suicide."
The detective extricated himself from John's grasp to properly, if not awkwardly, wrap his arms around the doctor's jumper-swathed waist. He returned the embrace, squeezing the detective comfortably. The words, spoken numerous times since his return, fought to escape his lips once more, but he forced them down.
John never reacted well to that truth.
"I'm sorry," John mumbled.
Sherlock pulled away, surprised by the apology, arms loosely wrapped around John. The doctor leaned forward, cupping the detective's cheeks.
"I'm sorry," he reiterated. "I just missed you so much. I still miss you. Things aren't the same."
He's drugged. He's drugged. He's drugged. He's speaking nonsense, painful nonsense, because YOU drugged him, Sherlock thought as John continued to close the distance between them, until mere centimeters separated their lips. None of this is real.
Predictably, John surged forward, pressing their lips together. Sherlock froze, unwilling to torture himself further by engaging in the delusion, yet, in the end, he couldn't bring himself to refuse John.
When they pulled away, foreheads pressed together, eyes remaining closed, John sighed. "You don't know how long I've wanted to do that."
Sherlock opened his eyes and stared at the doctor, enraptured by his enthralled expression. He truly meant the words, drudged from the depths of his denial-ridden subconscious. Despite their truthful roots, however, the detective knew it wouldn't last, knew he was never going to be top priority in John's life ever again.
Mary better appreciate what she has.
Sherlock committed the fleeting moment to memory, fearful that the drug's effects finally wore off, certain, however, that they had.
John's eyes remained closed, a gentle snore escaping soft, slightly chapped lips, and the doctor faded into sleep as Sherlock woke from dreams of shadow and light. They were too good to be true, he knew, yet the detective clung to them desperately.
Sherlock refused to entertain the hope that John hadn't forgotten, that his affection wasn't the sole product of an addled mind; however, it proved impossible for the detective to not estimate the chances of the memory's survival as he carried John to the couch and draped him in a blanket.
When the doctor woke hours later, immediately locking eyes with Sherlock, the detective knew it was too good to be true.
John had forgotten everything.