A/N: Something rather different from my usual lot. I've read a couple of dark stories now and wanted to try my hand at it. This is actually the opening chapter for a much longer story I have planned, but it isn't going to get written any time soon, so I figured I might as well post this for your titillation. Therefore please do not expect updates on this anytime soon. I noticed it got a bit Dexter and this worried me at first, but hopefully it's not too similar! Also, hooray first published slash smut! I'd be interested to hear if you like this kind of style, with the darkness and etc.

"Come on John!" Sherlock called after his companion who was struggling to keep up with him. John was not unfit (certainly not anymore) but Sherlock was high on the thrill of hunting prey tonight, not just being sated by the Work. For the energetic man, tonight was a gift to his friend and an indulgence for himself. John simply grumbled and picked up his pace. A nimble leap over a security fence and they were in the grounds of a disused industrial complex and Sherlock made for the cluster of warehouses in the centre of the grounds.

"What are we doing here?" John asked, panting with exertion; he hadn't seen Sherlock this excited or energised for a long time, not since a couple of months ago when he had last bagged a victim. He wondered if that was what they were doing tonight.

"It's a surprise, I know you'll like it," he said and John saw something in his eyes which he couldn't quite place. It was one of childish excitement, but there was a sinister sheen in his eyes which ignited John's own anticipation. It looked as though he was about to do something very naughty but very fun and by naughty he thought illegal. The detective lead him through the maze of buildings and the eventually ducked into a small warehouse and through the damp interior to the offices inside. He hovered outside the door, a naughty smile on his face.

"Ready?" he asked, almost overflowing with excitement. John nodded and the detective opened the door and turned on the light.

Sat, bound to a chair was the terrified Hugh Lane, uncaught serial rapist. His eyes widened in fear at the sight of Sherlock and trepidation as his companion laid eyes on him. It took less than a second for John to recognise Sherlock's latest victim and they darkened, the gentleness and care so usually present in them drained away into hard darkness and cold loathing. Sherlock loved to see that, to see John's demeanour change and slip into his other self who was cold, ruthless and commanding. When he was in this frame of mind he could tell Sherlock what to do and the taller man would respond instantly, thrilled to have someone who not only accepted and embraced his darker urges, but pushed them further.

"When you said you had a treat for me, I wasn't expecting this," John said, his voice lower and quiet as his mind worked and Sherlock watched with endless fascination as John seemed to give in to his shadow self. "You caught him for me?" he asked. Sherlock nodded, feeling satisfied. It was in these moments when he was indulging his own dark side that he felt emotions with great intensity and satisfaction, this was his norm, his true self. Normality drained away his feelings and he became a dumbed down version of himself and he thought that he would never be able to reveal himself to anyone (Mycroft didn't count). But he had met John, perhaps they instinctively could feel the other's capacity for darkness and eventually they opened up their shadows selves to each other and now Sherlock had not only an audience for his genius, but someone to indulge his darkness for, like a purpose.

John's face flickered into a smile, not his usual warm grin, but a satisfied smirk and he looked over to Sherlock with pride.

"This is very special," John said and circled the terrified man, his wild eyes trying to keep the doctor in his view. "Did he give you any trouble?"

"They all struggle, but he was out like a light in less than a minute," he said, watching John like a hawk, basking in every look of approval and pride from his partner. John loved seeing Sherlock like this; this was him unbridled and set free to indulge every part of his brilliant mind and it was beautiful. While John liked their domestic life and had fun on their cases, these were the moments when they felt truly alive. He gave Sherlock an indulgent smile and breathed in the smug expression in his partner's face in response.

"What do you want to do with him?" John asked, always giving Sherlock first call on what to do, after all, it was the younger's man's catch. A thousand ideas passed through Sherlock's eyes as he considered carefully for a few seconds what he wanted to do.

"Can we hurt him?" Sherlock asked aloud, wrapped up in his ideas. The man was sobbing and whimpering, knowing that there was no way he was going to get out of this. John could see Sherlock's fingers curling and flexing now, he was desperate to get started and wouldn't be held back any longer. John nodded in agreement and watched as Sherlock got to business.

The younger man left his coat on John's arm and reached down to the electrical cables he had dug out from the ceiling a long time ago and tested the grip of the shiny new crocodile clips on each cable, noting and delighting in the look of terror in the prey's eyes.

"It's nothing personal," John said as Sherlock completed his preparation. "You simply made yourself a target. We target those people who escape what should be coming to them and you left yourself wide open. Don't forget the bit, Sherlock. You don't want him to bite his tongue," John warned and Sherlock passed him a sardonic look.

"Of course I won't forget," he replied curtly and tore the sleeve from his prey's jumper, taking care to dislocate the shoulder as he did so and cut the material with the knife in his pocket. Hugh clamped his mouth tightly shut and Sherlock wasn't able to force the material between his teeth, so with a weary sigh he pinched the nose of the prey hard until he opened his mouth to breathe. With the speed of a striking cobra he forced the wool deep into the prey's mouth, stretching the lips wide and tying it neatly in a knot at the back of his head.

Sherlock took a step away and stared at the prey with such a heated intensity that the world seemed to stop for a moment. John quietly moved away, knowing that Sherlock needed a few moments time to concentrate. Sherlock didn't keep trophies, it was too dangerous, so he stored his momentos in his mind palace. The dungeons and catacombs of the palace were ever expanding to include all of his chosen ones.

After Sherlock had finished committing this prey to memory, forever enshrined in a dark cell in a corner of his mind, he placed the clamps on Hugh's arms and stepped to the side where a lever for the electrics hung on the walls. He wasted no time in pulling down the lever and watching as the prey completed the circuit. Muffled screams erupted from his throat as he fried, literally cooking from inside out. The smell of burning flesh quickly filled the room and Sherlock grinned, looking on at his work with pride and satisfaction. Sparks flew from the clips on the man and provided a pretty light show as it worked its magic in taking life. Sherlock leaned over and shared a kiss with John as the man's final screams left the roasting body, the killer's eyes alight with the high of satisfaction and tenderness in his appreciation for his beloved partner. They exchanged a small smile and went back to watch the last few moments of life in the prey, their hands firmly entwined.

It didn't take too long for the man to die and Sherlock soon pushed up the lever to turn off the electrical current. John opened the door into the main chamber of the warehouse and cleared the way to a small hut close to the offices, leaving the doors open. He left Sherlock's coat outside as he had to open a heavy metal lid on a deep pit, the smell from which was rancid. It was a deep shaft that was originally used to store water for the factory's use when there used to be industrial machinery in here. They had filled it with bleach and quick lime for dissolving corpses.

Sherlock made quick work of his task. He threw a tarpaulin over the corpse and chair and then knocked them over so he could gather up the ends of the plastic like a sack and drag the remains over to the pit John was unlocking as he worked. He was practised at this now and had the corpse over to the pit in under two minutes. John helped him tip the body into the pit and slammed the lid shut, relocking it. Sherlock was busy folding the tarpaulin when John languidly left the hut.

"You know where I'll be when you're finished. Don't keep me waiting," he said huskily as he walked out to leave the warehouse. Sherlock groaned, the voice of his soldier going straight to his cock and leaving him in a state of aching desire. As quickly as he could possibly could, he put the plastic into a bath tub filled with bleach as well as the crocodile clips, leaving them to soak and destroy any remnants of Hugh Lane. He threw his rubber gloves in there too before collecting his coat and running out of the warehouse full pelt. By the time he had finished locking up and had made it to the other building where he knew John would be waiting for him, the aforementioned doctor was laid on a mattress they had placed in there for liaisons such as this, sprawled over the fresh sheets.

When Sherlock killed like that he laid himself completely open, he was naked before the observer and being that onlooker it turned John on in a way he couldn't describe. He knew that Sherlock had bared his soul to him and in return John had pledged his everything to the younger man. Sherlock looked to John for approval that his naked self was embraced and loved and John never failed to provide that. For being privilege to that, John gave himself to the younger man's ardour and allowed himself to be fiercely claimed as he laid claim to Sherlock's soul.

The look in the taller man's eyes was predatory, but not in longing for a kill, it was pure lust and with his burning eyes alone John was breathless with anticipation and raging arousal. Sherlock threw his coat in a corner and was upon his lover in a matter of seconds, his mouth attacking the soldier's neck, his hands clasping the older man's wrists and pinning him down to the mattress, his groin pressing hard into John's erection. John groaned with pleasure as he was claimed by the serial killer who was on a high from his latest fulfilment. In this state Sherlock was frenzied, overflowing with pure lust and wanting; he was barely capable of speech in these unguarded moments, his mind free of restraints and allowed to dominate and claim John.

"Oh God, you were amazing in there," John moaned breathily, Sherlock's lips kissing, licking and sucking their way down his neck. "You have no idea how incredible you look when you're like this- Ah!" His words were cut off with a moan as Sherlock pressed down into his groin again. The younger man let go of John's wrists and immediately the soldier used them to roam his lover's fine body. Sherlock's breathing was heavy and he was panting with desire, his limbs tense and wired for strain.

"Clothes," he managed to say and John understood immediately. His fingers made quick work of the buttons of his lover's shirt and with a little whimper of appreciation he exposed the creamy white skin that he so loved to taste and feel. He also quickly divested himself of his jumper and shirt, knowing that if he didn't do so quickly Sherlock was in the kind of state where he would simply tear the material to get at what he wanted and there would be some awkward questions on the way home from the taxi driver as he tried to hold together the shredded remains of his clothes.

His newly exposed skin was instantly assaulted again by Sherlock's delectable mouth, the frenzied man on top of him almost devouring him in need. His soft lips traced their way to John's collarbone and licked sucked upon a sensitive bundle of scar tissue from the marks Sherlock made every time he claimed John like this. The doctor knew this was a sign that Sherlock wasn't going to hold back for much longer and he deftly undid both of their belts and kicked off his own trousers and underwear before freeing Sherlock of the rest of his cloth prisons. His mouth was once again taken by Sherlock's and he blindly reached over for the bottle beside the mattress.

John wondered as he struggled to pop the cap on the bottle if Sherlock was too far gone to do the preparation, it wouldn't be the first time he had had to hastily stretch himself before his lover buried himself inside of John. His question was answered when Sherlock snatched the bottle out of his hands and put his finger tips to John's lips. Immediately and greedily, John curled his tongue around the digits and sucked them into his mouth, swirling his tongue around them and imitating what he might do to Sherlock's cock next time they had sex. His eyes met Sherlock's animal ones and he felt his cock twitch in desire. Sufficiently wetted, Sherlock dragged his fingers from John's sweet mouth and pushed a finger into his lover's entrance, neither of them having the time or patience to take it slow. The very second John reckoned he was ready another finger joined the first and he bucked up, his cock brushing against Sherlock's swollen head and they both gasped; the younger man's fingers curling and hitting the spot which made John cry out, his lips forming a perfect O as he experienced the fleeting sensation.

"Oh God, Sherlock," he panted, already lightly sheened with perspiration from the anticipation. All he got in response was a guttural growl and he felt Sherlock scrambling for the bottle again. John's stomach flipped in excitement as he watched his lover pour a generous amount onto his hands and slather his weeping cock. As he did so, he bent over John again, his lips playing with the scar again and instinctively he bit down, causing John to cry out again with pleasure and pain. John was high, high from the arousal and from being claimed by Sherlock's ravenous mouth as a sign to the rest of the world that he belonged to the younger man.

John pushed his hips into Sherlock's and lifted his knees, practically begging to be taken. The darker man didn't wait, he pushed his cock into John and the two of them groaned as they were completed. As soon as Sherlock was comfortably inside the smaller man he snapped his hips forward, only managing a few stokes at a slow pace before he pinned John's wrists by his ears and bucked into him, fucking him furiously and slamming his lover's prostate with almost every thrust. John was thrashing about underneath him, his skin now glistening with sweat as he bucked to meet every snap of Sherlock's hips and primal grunts and moans worked out of them as they both quickly made it to climax. Sherlock snatched a few kisses here and there, but mostly he was looking down at his lover while his body worked furiously, their eyes locked and souls united while they built up to euphoria. His gaze meant only one thing 'you're mine' and John willingly gave himself.

Sherlock was shaking now as he moved, his muscles straining with effort as he pounded furiously into John, his climax almost upon him. John broke first.

"Sh…Sher…" was all he could manage to get out coherently before he cried out his orgasm to his lover, never once breaking eye contact. With a triumphant grunt, Sherlock felt John clench around him and he roared as he came, staring fiercely down at John, the bloody trickle from his earlier bite in the corner of his vision. John was his in every sense and every cell in his body felt it as his animal need was satisfied.