It was Christmas Eve, and John was frustrated. In more ways than one. Sherlock had refused to do any decorating for the occasion ("What's the point, John? Waste all that electricity on a couple of sparkly lights, just to take them down the next day?"), he and Harry had had a row a few days prior (barring the already negligible possibility of seeing family for Christmas), and lastly, he seemed incapable of keeping a girlfriend for more than two weeks at a time. All he wanted was to spend a peaceful evening with someone he loved, and instead he was on his way back from Tesco with jug of eggnog in one hand and and a bottle of Captain Morgan in the other. If he couldn't have his Christmas, he had the right to at least get more-than-slightly laggered, dammit.
He raced up the stairs to 221B, bottles swinging angrily at his sides. Sherlock had been out late all week, and John doubted that the fact that it was Christmas Eve would change that. He thought of the one decoration in their sitting room, a small, scraggly pine tree he had bought on a whim at a Christmas market. There was a single gold-wrapped box peeking out from beneath its branches, addressed "To: Sherlock, From: John". Inside were a dozen nicotine patches; Sherlock had run out weeks ago, and though he of about not having any, John knew he wouldn't buy them for himself. He thought as Christmas neared that another gift might materialize alongside his own. He should have known that as far as Christmas spirit went, Sherlock outdid the Grinch and Scrooge combined.
John sighed one last time before pushing through the door to their flat.
"Sherlock? You here?" he called. No response. He plunked both heavy bottles down on the coffee table, turning to enter the kitchen for some glasses. "Right, well," John muttered, "wouldn't expect you to be, would I—"
He stopped cold in his tracks, inches from Sherlock's chest. John blinked confusedly, his mouth moving in silence. Slowly, he looked up, his gaze lingering first on his flatmate's stern expression, then on the single strand of mistletoe dangling directly above their heads.
"John. Don't. Move." Sherlock uttered through clenched teeth, his eyes flashing menacingly.
John had finally regained the capacity of speech. "Sherlock, what is this?! What is… that?" he sputtered, gesturing at the plant swaying innocently above them. He knew full well what is was.
"Don't let looks deceive you John, that plant is not mistletoe, " the deceptive hissed impatiently. "Notice the slightly serrated edges, the berries that are more opaque than translucent. Someone has planted this… plant here for a reason. They mean to kill us." His eyebrows furrowed, and he glared at the gangly greenery as one would a misbehaving child.
"To… kill us?!" John stammered, disbelieving. "Surely Sherlock, that weed couldn't kill us. And anyway, all we'd have to do is chop it down…" He shifted slightly, in preparation to step out of the way.
"NO!" Sherlock shouted, grabbing John's wrist tightly, keeping him in place. "You haven't understood a thing. What we're facing isn't mistletoe, but its deadly Amazonian cousin, Viscurum album. It is a rare species known for its uncanny ability to sense human pheromones. If it doesn't sense our pheromones, or for some reason they aren't strong enough, it will drop all its berries right here and now. The chemical their juice contains is highly toxic, seeps in through the bloodstream, and is therefore fatal upon contact." Sherlock's electric grey eyes were now locked on John's with unnerving intensity.
"Well… then…" John murmured. "How do we continue to release pheromones?"
Before John could breathe another word, Sherlock's lips met his. Though John stood as still as a statue, shocked beyond belief, he felt a white-hot currant course through his body. Pheremones.
"Right, then. For the sake of not getting killed…" He began to move his mouth against Sherlock's, biting softly at his flatmate's lower lip. The fiery sensation had spread to his fingers and toes, which were now tingling with explosive energy. To his surprise, Sherlock let out a quiet moan. The detective's hands moved to grip John's stubbly face. After a moment's hesitation, John's tongue moved slowly inside the taller man's mouth, gently exploring its crevices. This elicited a somewhat louder moan from Sherlock, his torso melting slightly until John felt the heat of his flatmate's chest against his own, separated only by layers of thin, scratchy fabric. "Is this really… Science?"
John now felt the electrifying warmth moving decisively to certain… nether regions. It was his turn to groan, involuntarily grinding his groin against Sherlock's long, bony thigh. His thoughts dissipated, floating from him like snowflakes blown from an open hand.
Sherlock had felt John's arousal, and reacted in kind. He clasped the doctor tightly against his long, slender frame, rubbing his thigh suggestively between his flatmate's legs, his head moving down to suck on the sensitive skin of John's neck. John gasped and threw his head back, succumbing and softening at Sherlock's touch. The detective began unbuttoning the shorter man's grey plaid shirt, kissing his way down John's chest, biting and sucking each pert nipple.
"Sherlock," John gasped, his voice raspy with lust. "Please." He fumbled with his belt, finally casting it aside and dropping his trousers eagerly. Sherlock was now on his knees, face to face with John's white pants and the unmistakable bulge they contained. He lowered them carefully, smiling when John's thick member sprang to meet him. Sherlock took it deep into his mouth, to the hilt. He began sucking, working it, circling the tip with his tongue and massaging John's balls in his long, dexterous fingers. John practically screamed in ecstasy, his body quivering with delight. He had never pictured, never imagined—Sherlock. But it was good, better than he'd ever had, and he grasped at the detective's gorgeous black curls as the man pumped him back and forth. Finally, John came, groaning with pleasure, pouring his seed down Sherlock's throat. His flatmate licked his lips and rose to face him, a slight smirk hovering on his lips.
John saw the man like never before. His translucent skin, stormy eyes, and jutting cheekbones were positively delectable. His button-down shirt was slightly askew, revealing a piece of pale, sinewy flesh. John wanted nothing more than to lose himself in Sherlock's forest of black curls, to chart every inch of the man's skin. He wanted to please Sherlock in the most primal way, and the detective's dilated pupils and flushed cheeks told him he would have his Christmas present after all.
John wasted no time, tearing off Sherlock's fitted purple shirt and making short work of the man's silver belt buckle. He lowered his flatmate's trouser's with enthusiasm, pants not far behind. Sherlock was soon standing in front of him, stark naked. John drank in the long, lean frame, the defined chest, the subtle line of hair leading down to… A shaft tall and long like its owner, standing erect. The doctor moved in closer, taking it in his hand, stroking it from base to tip, hearing Sherlock's breath hitch in his chest.
"Sherlock… I know what I want for Christmas," he whispered into his flatmate's ear.
"And—what would that be—John?" Sherlock replied in gasps, finding speech rather difficult as his throbbing member was caressed by Watson.
"I want you… To fuck me," John whispered, drawing out the last two words devilishly. Sherlock moaned loudly, grabbing John by the arms and leading him to the sitting room couch. He started by inserting a finger into John's hole, then two, waiting for the muscles to relax.
"Ready?" he rasped. John nodded definitively. Sherlock inserted himself slowly, inch by inch, causing John to gasp loudly. There was pain at first, but… The feeling of Sherlock filling him was a kind of completion he had never experienced. And, finally… A shock of pleasure as Sherlock's tip brushed his prostate. John moaned, and Sherlock took this as a signal to begin, thrusting again and again, slowly at first, then faster.
"Oh, John," Sherlock gasped, "You're… marvelous." John only growled in equal pleasure as his flatmate's pounding brought him closer and closer to the brink of absolute bliss. Sherlock picked up the pace, slamming John against the sofa, both detective and doctor drowning in ecstasy. Sherlock brought his hand to John's cock, jerking him off in time with his thrusts, driving them both over the edge. Sherlock came inside John, arching and quivering with pleasure, as John's seed sprayed his hand. They rode wave after wave of pleasure until collapsing, breathless, onto the leather sofa.
"John?" Sherlock finally spoke, stroking the detective's cheek gently. He smiled as the doctor's eyes met his. "Merry Christmas."
"Merry Christmas, Sherlock," John replied with a grin. Suddenly, he frowned, brows furrowing. "Wait a minute…" he breathed, "it was just ordinary mistletoe, wasn't it?"
Sherlock smirked knowingly. "Yes, John, just ordinary mistletoe. Obvious to even the most amateur botanist. But, luckily for me, you can't so much as tell lilies from lilacs."
John scowled, smacking his flatmate's arm lightly. "You bully!"
"Oh, not so much a bully as a schemer, John. And look! Where would you have been without me? Getting yourself inebriated with the help of spiked eggnog and moping about. Instead, we had a perfectly congenial Christmas Eve, wouldn't you say?" Sherlock winked, kissed John lightly on the forehead, and slipped out from underneath him, making his way toward the center of the room.
"Where do you think you're going?" John demanded. Though he had gotten his present, he wouldn't mind spending Christmas morning wrapped in his flatmate's long, delicate arms.
"I fancy a smoke," Sherlock replied offhandedly.
"But Sherlock, you're not supposed to—" John began, stopping suddenly when Sherlock grasped his gold-wrapped box between his wiry fingers. Ripping the paper away lightly, he opened the box and extracted a single nicotine patch. Pressing it to his arm, he strode back toward the doctor.
"How did you know?" John asked, for what seemed like the thousandth time. Sherlock only smiled, straddling the doctor.
"Oh, John. I knew from the self-satisfied look on your face the moment I first said I was out of patches. I played along, of course. And decided I should give you a little something in return. Hence the mistletoe." He leaned down, kissing John passionately on the mouth. After what seemed like several hours, John caught his breath enough to reply.
"Guess you're not such a Grinch after all," he admitted, smiling into Sherlock's warm, woolen grey eyes.
"Oh, John. I may not care so much about Christmas, but I always care… I always think… And I always know." With that, he rested his head on John's chest. Lying perfectly peacefully, perfectly still, wrapped in each others' arms, the doctor and the detective drifted into a restful Christmas sleep, knowing their mistletoe would be there to greet them come morning.