The first time it happened, Sherlock had been aware that he had been breaking every flatmate agreement set up by flatmates around the world. Still, it hadn't stopped him from trying to rationalise the behaviour. At the time, he had told himself it was a matter of convenience; he had been working on a very important case and researching some crucial information on his BlackBerry had required the use of his two hands. He had told himself that since people's lives were at stake, it was unacceptable to cease his research even for the few minutes required to find release and get rid of the very distracting erection that had been plaguing him for the last twenty-two minutes.

It hadn't taken long for what had started off as a low buzzing inconvenience in his abdomen to erupt into a wild fire, consuming his insides while something low and primal had beaten a demanding rhythm in his groin. He had been unable to think about anything other than the solution he had had in mind and the voice screaming want want want inside his head. Which is why, after the thirty-seventh minute of being hard, he had made his way upstairs, both reluctant and excited.

For once, he had been grateful for John's job at the surgery, which had kept him out of the flat on that particular afternoon. John's bedroom had been dark, the curtains still drawn, but it had been easy to make out the shape of his therapy pillow on the bed. Sherlock hadn't thought much of the pillow at first when John had brought it up to his bedroom with the rest of his things, but that changed when he had barged into the room and seen John sleeping with an arm and leg around the thing. After that night, his dreams had been filled with images of John and the pillow; sometimes he was just sleeping with it, but mostly he was doing things to it that would have made the Marquis de Sade blush. It hadn't been long before Sherlock had started imagining doing naughty things of his own to the pillow.

That's why he had found himself in John's room, completely naked, straddling the pillow and squeezing it with his thighs, his hips rocking back and forth as he stared at his BlackBerry. It had been very important to continue reading; the whole experience would have been pointless if he had stopped working. Since that day, he had become well acquainted with the now familiar urge and he had indulged numerous times. However, he had abandoned all pretence of using his phone when he had realised that the actual work had been replaced by hitting the 'Random article' link on Wikipedia. Masturbating in his friend's room had been disturbing enough, but staring at a page about the 1991 Australian Motorcycle Grand Prix had only made things worst.

As months went by, the urge to go up to John's room and assault his pillow became stronger and harder to ignore, to Sherlock's utter dismay. The frequent arousal was very inconvenient and he found it hard to concentrate on the work when it felt like most of his blood rushed to his cock, to the detriment of his brain. It's why he so often found himself waiting expectantly for John to leave the flat.

Earlier this particular morning, John had woken up late, had taken a quick shower and had come down the stairs wearing only a tight fitting pair of boxers. He had rummaged through the bag he had brought back from the launderette the day before but hadn't bothered to take up to his room, preferring to drop it just inside the door to 221b and joining Sherlock on the sofa for their afternoon session of Bargain Hunt. Sherlock had watched the scene unfold from his comfortable position on the sofa and had managed to retain an exterior of calm as his eyes had detailed John's strong muscles under what looked like a very soft belly, the noticeable bulge in his boxers, the powerful thighs sprinkled with golden hair, the curve of his arse as he had bent down to reach into the bag…. It had lasted no longer than forty seconds, but Sherlock had reacted as naturally as Pavlov's dog and instantly his thoughts had drifted upstairs to John's bedroom – specifically to John's bed. When John finally closed the door behind him to meet his sister for breakfast, Sherlock didn't even try to convince himself that it wasn't going to happen; he got up and made his way up to John's bedroom.

He was half hard already when he entered the room and breathed in the scent of John that impregnated the place. For the first time since he had started to indulge in that blissful pleasure of his, the bed was unmade. Sherlock silently thanked John's faulty alarm clock that had made him late that morning, causing him to leave in a hurry without making the bed, as it meant Sherlock could truly immerse himself in John's sleeping area. The sheets were tangled, John's sleeping form could still easily be imagined among the mess and, when Sherlock sat on the bed, he realised it was still warm. The thought sent a rush of tingles down his spine. Taking a deep breath that arousal made shaky, he lay down on his side and buried his face into the cotton sheets that smelled very strongly of John with a small hint of night sweat; Sherlock's mind instantly noted that John had most likely tossed and turned a lot in his sleep. Nightmares.

As he always did, he took off his shirt but kept his pyjama bottoms on, under which he wasn't wearing any underwear. His cock gave a slight enthusiastic twitch when he turned to lay on his front, the warm sheets like a soft caress on his naked chest. He stayed like that for a long moment, inhaling the delicious scent of John and only shifting once in a while to adjust his hardening cock. His body was almost immobile, but his mind was ablaze with images of John, working frantically, jumping from one scenario to the next. He imagined his friend's strong thighs straddling his hips, his hard cock brushing teasingly against his lower back. He imagined John leaning down to whisper his name in a voice husky with desire, biting his earlobe and chuckling upon hearing Sherlock's groan of approval. He pictured John shifting down until he could rub his cock in the cleft of his arse, spreading pre-come in the process and teasing his hole.

When the need to thrust into the mattress became too strong to ignore, Sherlock turned his attention to the reason he sneaked up in John's bedroom so often, what kept him coming again and again. Pun very much intended, but Sherlock could forgive himself; the only thing occupying his mind at that moment was the pleasure already sparkling through his body. He turned his head and looked at John's very large body pillow that had been half thrown off the bed.

The therapy pillow had been a recommendation of John's physiotherapist; sleeping with his left arm wrapped around it helped decrease the pressure off his wounded shoulder and reduced the pain he sometimes felt when he woke up. John had been a little embarrassed to buy an object usually advertised to pregnant women, but all embarrassment had been thrown out the window when he had realised how beneficial the pillow actually was. When he had moved in to 221b Baker Street, the pillow had moved in with him and soon after, Sherlock's fascination for the thing moved in, too.

John, however, wasn't aware that his flatmate also found the body pillow very, very beneficial.

Sherlock rolled onto his side, kicked off his pyjama bottoms and dragged the object of his fascination back onto the bed. His heart rate was already abnormally fast as he folded the pillow in two and straddled it. Then, he leaned forward until he could nuzzle it, once again getting drunk on the scent that was pure John. He could feel his cock trapped between his stomach and the fabric, and he teased himself by shifting his hips up and down to feel the reward of a soft friction. For a few minutes, he was content to slowly rub his cock forward and backward on the pillow, imagining a soft belly and a trail of golden hair getting darker the closer they were to what he imagined to be John's fairly large and thick cock.

As the urge to thrust thrust thrust grew, he squeezed the pillow tighter with his thighs and sat up straight, his legs bent at 45 degrees angles and toes almost touching behind him as his arse ground into the fluffy material. He imagined what John would see if he came into the room right now, how he would react to seeing Sherlock's muscles move under the very slightly flushed pale skin. Would John admire the silent strength of his deltoids and trapezius as he clutched the pillow? Would he want to put his hands on Sherlock's latissimi dorsi? He could feel them shifting as his vertebral column undulated with his thrusts. Would John grip his hips with enough force to leave bruises? Would he stand back a little to admire Sherlock's gluteus maximus? Would he lick his lips like he did so often?

Thinking about the shy, pink organ peeking out of his friend's mouth made Sherlock grunt and he thrust harder, feeling the give and take of every muscle in his buttocks, his arse moving in slow waves. When he spread his thighs a little wider, he felt his arse cheeks spread and knowing how exposed his anus was made his cock pulse with increased arousal. He kept the same rhythm until the pressure building in his groin was almost unbearable. Then, he supported his weight with his knees and hands to lift his hips upwards, his engorged cock hovering an inch away from the pillow. The sound of his laboured breathing filled the room, his ears, and his mind.

When he was practically begging for a touch, he resumed his very slow tantalizing motions, his cock barely brushing the pillow. He kept that rhythm until his heartbeat slowed down a little; the point of this intimate ritual wasn't instant gratification achieved from immediately rutting frantically against the pillow like an animal that would have him coming within five minutes. He wanted to enjoy it, to make it last, to immerse himself in the sensations until he could almost believe that John was writhing under him, that it was John's thighs between his thighs, that it was John…. He shuddered, dropped his chin to his chest and let out a low, breathy groan.

Soon, the slow teasing wasn't enough and he braced himself on his hands and toes, raised his arse higher into the air before thrusting violently up and down, burying his cock deep into the fluffy material. His strokes were wide enough to stimulate his balls, but as pleasurable as the movements were, he knew it wasn't a rhythm he would be able to keep for long. The surges of pleasure were intense, but too few and far between and he needed more. His cock was starting to leak precome and, as usual, he was desperately turned on by the trace of himself on John's pillow, on a place that John had touched merely a few hours before. The thought made him grunt possessively and he buried his cock into the fabric, his arse rippling as he ground deeper and deeper.

He was starting to sweat with the effort, his curls falling in front of his closed eyes, but he ignored it and he gripped the pillow tighter in front of him, offering more support as he shifted to find a better angle. Gritting his teeth, he made a few very quick movements with his hips that broke some of the control he had left and elicited his first genuine moan, a moan that he pretended John had just made. In response, Sherlock pressed his cock harder against what he imagined was John's length and he rode the pillow with more force, ignoring the fact that his biceps were starting to shake. Instead, he concentrated on the fire in his thighs, the tickling feeling in his arse and particularly around his hole that he imagined John was teasing with a single adventurous finger.

His coccyx felt like it was on fire and the delicious burning sensation was spreading upwards as his spinal column curved languorously. By then, he had abandoned all efforts to regulate his breathing and he was panting shamelessly, which aroused him even more. He knew that he was getting there; the scorching feeling had escalated to his lumbar vertebrae and he could feel a very familiar tightening in his balls. The wet patch on the pillow had grown considerably larger and he pretended the moisture was the product of his and John's shared pleasure.

He knew his release was imminent when the pleasure intensified in his groin and spread to his lower thoracic vertebrae. In order to feel more of John pressed against him, he lowered his upper body until he was fully lying on the pillow. He spread his legs wider, keeping his knees bent, grabbed two fistfuls of sheets and started rutting desperately, finally working towards an orgasm he knew would be nothing less than mind blowing. Using his whole body to push himself upward and backward again and again, he still managed to move gracefully despite his primal position. His toes curled and uncurled as he used them for leverage to push with more intensity and he squeezed his arse to grind into the pillow with all the force he could manage in his heated state. When he felt the urge to scream himself hoarse, he buried his face into the soft fabric and let out a stream of noise that wouldn't have been out of place coming from the mouth of a panther. He filled his lungs with the smell of John and, after a few more frantic thrusts, he came.

Even if he was used to the encounters with John's pillow, it always surprised him how liberating his breathless orgasms were. It was almost overwhelming, like trying to fit a grapefruit-sized ball of pleasure through his urethra. His whole body stilled, save for small involuntary tremors in his arse and thighs, his eyes rolled back behind his closed pupils and his mouth opened wide as a strangled cry escaped his lips. Then, as spurts of semen shot out of his cock, his hips gave a few small and uncontrolled thrusts into the pillow that didn't stop until the last drop of semen had left his body. For long minutes afterwards he lay panting, still wrapped around the pillow and seemingly unaware that he was resting in a mess of come. He always took some time to enjoy the contentment and bliss that came afterwards, the calm and quiet before his brain kicked in and the world started up around him again.

After a while, he got up to scrub the pillow vigorously with a wet facecloth and replaced it in its previous position where it would dry during the day, no traces of Sherlock's debauchery remaining when John would go to bed. He picked up his pyjama bottoms and went to their shared bathroom to have a long shower where, exhausted, he slumped down against the wall while water washed the remaining incriminating traces of his indulgence down the drain.

When he turned the shower off, he heard some noises downstairs: John was back. He was back earlier than Sherlock had anticipated; something must have gone wrong during his meeting with his sister – an argument about her drinking no doubt. Dull. Predictable. It should have been predictable, but the haze of lust that had overwhelmed him at John's impromptu show of nudity had left little space for rational thought in Sherlock's mind.

With his cheeks and chest still flushed – but that could have been caused by a too hot shower – he put his pyjama bottoms back on and went downstairs to inquire about what had happened.

Halfway in the living room, he remembered that he'd left his t-shirt on John's bedroom floor.