A/N: I was working on a different story when this idea came to me. How did John get kidnapped a second time without being whacked upside the head with a pistol and tied up? Maybe a little like this... Enjoy!

Closing the door behind him, John shook his head in wonder. Offering to go shopping was a new one; just imagining his reclusive flatmate who loathed all tasks bordering on the mundane pushing a shopping cart made him grin. If Sherlock was anything, it certainly wasn't predictable.

Wiggling his fingers into his gloves, he debated going back for a warmer coat. It was a long walk to Sarah's, but the night was brisk and cool and he decided it would be nice to take a stroll in a decent part of London for once. Ever since he met Sherlock, he seemed to either be riding in cabs—something he'd never done much because of the expense—or jogging through the more distasteful parts of London. So, turning up his collar and stuffing his hands in his pockets, he started walking.

He made it as far as the Chinese restaurant on the corner, the one where he and Sherlock would often stop after a late night of chasing criminals and argue about the fortune cookies. He had started to turn onto Marylebone when a large hand clamped onto his shoulder and the barrel of a handgun wedged into his side.

"This way, Dr. Watson," a gravelly voice rumbled in his ear and before he could raise his voice or fight back he was shoved into an idling black car. There was the unmistakable tearing of duct tape as a piece of it was roughly plastered across his mouth and a pillowcase was yanked over his head. John tried struggling until two large hands, one on either side, gripped his arms firmly and kept him still. His shoulder throbbed with each bump and pitfall and he could feel his left hand shaking—Damn tremor—and he wondered if Sarah would call the police when he didn't show up.

It seemed to John as if he had sat in the muggy car, his entire left side aching from stress, for hours before they finally pulled over and he was shoved out again, the gun still digging into his ribs and his wrists viciously wrenched behind him. He heard the sound of a metal door swinging wide and slamming shut and the echo of their shoes along tile. In moments, the pillowcase was saturated with the heavy stench of chlorine that hung in the air around them. Telling himself this was no different from Afghanistan, he managed to calm his heart enough to be able to think. Sherlock's didactic baritone resounded in his ears: You see, but do you observe? Details, John. Tell me where you are. So he observed.

They were in a building—he knew that because of the doors and the echoing tiles. Tiles were used in places where things could be dropped or spilled, so perhaps a public building. And they were somewhere with water, because that's what chlorine is typically used for.

It came to him just before the pillowcase was jerked off and he read the words on a sign. He was at a public pool—specifically, the men's locker room at a public pool. Well, there's the question of 'where,' he thought as one of the men pushed him onto the concrete bench in the center. I wish I had my gun.

While he was lamenting the loss of his Browning, he heard another door open and his eyes naturally turned toward the sound. He wasn't surprised to see a tall, bulky individual with a bushy mustache, curled lip, and several pale scars crisscrossing his face—he looked like a person who would hold a grudge and kidnap someone. He was surprised, however, to see Jim from IT step out from behind him and smile pleasantly at John.

"Hello Dr. Watson," he said lightly as he waved away the men guarding him. They quickly vanished as the other man lazily aimed a handgun at his torso. "Colonel, would you mind removing the tape so Dr. Watson and I can have a proper talk?"

He said it so sweetly and politely that John forgot to prepare himself for the tape removal. He hissed in pain, his lips stinging, as the man tore it off his face and dropped it on the bench beside him.

"That's much better," Jim from IT said, moving forward to straddle the bench and smile at him. Instead of the V-necked shirt and bright green underwear, he was dressed in an elegant ebony suit and his voice held a distinct Irish brogue. "How are you, Doctor? So sorry to have diverted you from an evening with Dr. Sawyer, but I wanted to talk."

John was so befuddled the question tumbled past his smarting lips before he could stop it. "You don't work in the IT department, do you?"

Jim from IT laughed and the sound of it hurt John's ears. It was laced with confidence and arrogance and underscored with malice, the complete opposite of the nervous man flirting with Sherlock in the hospital lab. "No Doctor, I'm afraid not. It was a good cover though, don't you think?"

"Who are you?" he asked, ignoring the question. The adrenaline was back and he felt like he was meeting Mycroft Holmes all over again. He vaguely hoped this meeting would be as innocent as that one, but then he remembered neither Mycroft nor Anthea had ever pointed a gun at him. Annoyance bubbled in his throat as he narrowed his eyes. "What do you want from me?"

A cruel smile spread across Jim from IT's mouth. "You're his weakness, John," he whispered simply.

In that instant, everything clicked. "You're him," John murmured, shocked. "You're the bomber. You're," the name was barely a breath, "Moriarty."

"Verygood, John," Jim Moriarty said, clapping his hands gleefully. "There's hope for you yet."

He remembered Sherlock's careless words, how caring about people wouldn't save them, and that here was the man who had taken those lives in the first place. "You won't get away with this," he growled. "Sherlock will stop you." Inner John slapped his forehead; even he realized how cliché that sounded.

Moriarty smirked. "No, I really don't think he will. For all the wonderful things Sherlock Holmes is, selfishness isn't one of his better qualities. Then again, who am I to judge?" He clucked his tongue at John's confusion. "Come on Johnny boy, even you must have noticed how much fun Sherlock's been having with my little game. He doesn't want the fun to stop any more than I do."

"At the expense of others." John ground his teeth in anger. "He'll stop you because you're a criminal."

He grinned, but it was no longer pleasant. "You have a lot of faith in a man who was willing to take a poisonous pill just to prove he was right."

"You have a lot of faith in a man you don't even know."

But Moriarty shook his head. "Sherlock and I are two sides of the same coin. I can predict his every move and he thinkshe can predict mine. But if he could," and he reached out and grasped John's chin, twisting it painfully, "he wouldn't have let you out of his sight for a minute."

John shook his head viciously, shaking off the clammy hand before glaring at him. "What the hell are you going on about?" he snapped. "I'm his flatmate, not his lapdog."

"For years, Sherlock's prided himself on being invincible," Moriarty continued, studying his fingernails, his head oscillating slightly like a snake's. "I couldn't strike sooner because the man had no weaknesses." Then his face twisted into an ugly sneer. "And then he met you."

John's heart stopped. "You're wrong," he murmured, but he could taste the denial on his tongue. "He wouldn't… he doesn't…" He trailed off, bitterness mingling with the denial. Now he understood what Sherlock meant, why he refused to care about the victims. Because caring was not going to save him. He was Sherlock's downfall, the chink in the armor, and Moriarty fully planned to exploit that. The thought made him so sick all the fight drained out of him.

Moriarty's smile reappeared, as hateful and malignant as ever. "And now it's time for your big debut, Dr. Watson," he said, gesturing over his shoulder at his companion. "I hope you'll be better than my other volunteers. They were all so weepy. It completely ruined the effect."

The man hauled John to his feet and jerked his arms through a vest of some kind. As Moriarty snapped the buckles in front, he glanced down and saw colored wires and many blinking lights. Just like the others, he thought blandly as Moriarty cinched it tight.

Something brown and furry was waved in his face as the man handed him a parka and John zipped it up to his throat. "I don't want to spoil the surprise," Moriarty whispered as he gently inserted a plastic earpiece in his ear and tucked the spiraling white cord beneath the wired vest. "You're a clever boy, John. I assume you know how this works?"

"Repeat what you say or I get blown up," he mumbled mechanically, his mind empty.

Patting his shoulder, he grinned. "That's a good chap. Now, you just wait here for my cue." He exchanged a few words with the man, something about positions and lasers, as one of the men from before returned and directed John to another door, hand firmly clasped on his shoulder. There was the brief crackle of static in his ear before the outer door slammed, leaving him with the heavy hand on his shoulder and the fading hiss of Moriarty's voice as he turned on the microphone: He was invincible… until he met you.

He did not wait long. He hadn't expected him to walk right into Moriarty's trap, but Sherlock's low voice reverberating just beyond the door was unmistakable. "That's what it's all been for, isn't it?" he asked snidely. "All your little puzzles, making me dance, all to distract me from this." John swallowed.

"You're on, Dr. Watson," Moriarty purred into the earpiece as the man released him. Pressing his palm against the bar, he pushed forward and stepped onto parched tile. The harsh fluorescent lights reflected off the chlorinated water gently lapping the pool's concrete sides, and John turned to face the only man he had ever decided to trust. He had never seen Sherlock Holmes look so confused.

"Evening," he said, Moriarty's voice bouncing around in his head. "This is a turn-up, isn't it Sherlock?"

The confusion deepened, transformed into something else. Hurt. Pain. And John was ashamed to have caused it.

"John," Sherlock breathed, bewildered. "What the hell?" John could almost see the brilliant mind whirring behind his pale eyes, the pieces fitting and falling together, and his brain jumping to the wrong conclusion. He thinks it's me, he thought weakly. He thinks I did all this.

"Bet you never saw this coming," he said, his voice cracking mid-sentence because it hurt to see the betrayal welling in Sherlock's eyes. He wanted to reject it, John could tell, refuse and deny the logic because it meant he had misjudged John's character, but it was a losing battle. Of everything that had happened to him, the war and Shan and being bloody shot, the reluctant acceptance of miscalculation looming in the ice-blue eyes wounded John the most.

Moriarty loved it. He giggled in John's ear, greatly amused by the whole event. "Open your coat, Doctor. Let's not keep Sherlock in suspense for too long. Then…"

"What… would you like me… to make him say… next?" And he parted the stuffy parka as a red light flickered to his chest. Relief momentarily bloomed in Sherlock's eyes before they hardened again and he began to step toward him.

"Ooh, this is fun. John, say…"

"Gottle o' gear," John mumbled. "Gottle o' gear, gottle o' gear…"

"Stop it," Sherlock ordered. He was only five feet away now, close enough to be killed by the bomb, close enough for John to see a familiar outline in his jacket pocket.

"Nice touch, this," Moriarty sneered. "The pool, where little Carl died."

"I stopped him," he murmured. "I can stop John Watson too." He glanced down, saw the laser center on his chest. For the first time fear began to gnaw at him and he choked on the next words. "Stop his heart."

Sherlock heard it and his eyes flashed. "Who are you?" he shouted, his eyes scanning the roof.

The earpiece went dead even as a low, whiny voice sang out, "I gave you my number. I thought you might call." He saw Sherlock's eyes narrow and heard Moriarty's footsteps on the tile, watched Sherlock draw the revolver from his pocket and aim it across the pool. Heard the singsong tone. "Do I really make such a fleeting impression? Although I suppose that was rather the point."

Sherlock lifted his other arm to steady the gun, aim it more resolutely at Moriarty's head. The laser was still there. It made him cringe to look. When he tilted his head, Sherlock's jerked toward him reflexively, and Moriarty's voice rang out.

"Don't be silly," he said. "Someone else is holding the rifle." His voice dropped. "I don't like to get my hands dirty."

Halfway through Moriarty's villain speech, John stopped listening. It wasn't like the speech was for his benefit anyway, although he listened long enough to roll his eyes at Sherlock's grudging admiration of Moriarty's chosen 'profession.'

Sherlock finally brought him back to reality. John hadn't heard the question at first, but he heard his rough, strained voice and raised his head. His flatmate was staring at him, shoulders tense and stiff, mouth pressed into an almost invisible line, the gun pointed just beyond his shoulder.

"You can talk, Johnny boy," Moriarty said mockingly, leaning in too close. His cool breath fanned across his skin and sent goosebumps racing up his arms. "Go ahead." But John didn't talk because he couldn't; the terror had lodged in his throat, closing it up so he could barely swallow, but he forced his head to dip slightly. Yes.

Moriarty glided past him to accept something in Sherlock's outstretched hand. "The missile plans," he hissed. It took a moment for John to register Moriarty had stopped just in front of him but facing Sherlock. A glimmer of an idea began to take shape and as Moriarty carelessly tossed the memory stick into the pool like he was skipping stones, John darted forward and wrapped an arm around his neck. "Sherlock, run!"

Sherlock started but quickly covered it with a jolting swivel of the gun. But he didn't run. Moriarty found the whole episode hilarious; he didn't struggle in John's grasp except to tilt his head back to taunt him some more.

"You've rather showed your hand there, Dr. Watson," he tittered. John's eyes widened as a glowing red circle, like a pinpoint of blood, appeared in the center of Sherlock's forehead. He had no choice. He let Moriarty go.

After he stumbled back, hands in the air to show he was harmless, the entire mood of the pool seemed to change. Granted, it wasn't very cheery to begin with, but Moriarty, when prompted by how he would respond to Sherlock's continued 'meddling' in his plans, hunched forward and snarled, "I will burn the heartout of you."

Sherlock didn't flinch, didn't even blink. Instead he deadpanned, "I've been reliably informed that I don't have one."

For the most part, John thought, perhaps a little treasonously as he recalled their argument about caring.

He could hear the snarky, knowing grin in Moriarty's voice. "But we both know that's not quite true." And in the barest of movements, Sherlock's eyes flickered.

"Well, I'd better be off," he continued. "It was so nice to have a proper chat."

Sherlock raised the gun, but he didn't shoot. Even if he did kill Moriarty, surely the man with the scarred face would gladly shoot John, ignite his vest and blow their bodies to kingdom come. Moriarty moved to leave and they exchanged parting words and it was all very dramatic and belonged in a Bond flick, not a deserted pool, and then the door slammed behind him and Sherlock started pulling at the parka.

"Are you all right?" Sherlock snapped, his fingers frantically tearing at the buckles.

"Yeah, yeah," he murmured, still in a daze. "Yeah, I'm fine." The parka fell away from him. "I'm fine. Sherlock." Yanking at the vest, Sherlock pulled it and half of John's sweater off in his haste to remove it. "Sherlock!" Jerking it off, Sherlock shoved it along the tile so it slid halfway across the pool. He glanced at John before picking up the gun and darting out into the hall.

John started to follow but his legs wouldn't cooperate. His knees buckled and he wobbled over to the wall, clutching it for support as he slid down, the blood pumping loudly in his ears. Sherlock returned a moment later and paced in front of him, absently scratching his head with the barrel of the cocked revolver. John was too weak to chastise him.

"That, uh… thing that you, uh… that you did," Sherlock muttered, pacing and clearing his throat, "you offered to do, that was…" he coughed, "good."

Had he been in a better state of mind, John might've teased him. You're so eloquent, Sherlock. Do you mean grabbing that psychopath in a chokehold while wearing a vest stuffed with Semtex? That was nothing. Had he been in a worse state, he might've screamed. Why the hell didn't you run when you had the chance? What on earth were you thinking, you idiot? But because he wasn't entirely sure what kind of state he was in, John settled for a weird combination of the two. "Well, I'm glad no one saw that."

Sherlock glanced at him, his brow furrowed. "Hmm?"

He tried to sit up, tugging at his sweater's dislodged sleeve. "You, ripping my clothes off in a darkened swimming pool. People might talk."

Sherlock shrugged. "People do little else." Then he grinned breathlessly.

John started to laugh, grateful he was still alive to make ridiculous, nervous jokes. But just as he started to crawl up the wall and straighten up, something red flashed across his chest. Three red somethings. Sniper lasers. The laughter drained out of him like water in a punctured pail as three more lasers glittered over Sherlock's snowy shirtfront and Moriarty's cheerful Gaelic accent echoed around them once more.

"You can't be allowed to continue," he said. "You just can't."

They had few options left and they both knew it. Sherlock's eyes tilted toward him, clear and cold, a question hovering within the icy blue irises. Do you trust me?

John didn't even hesitate. In the barest of movements, he nodded his head, once. Yes.

The gun swiveled, lowered from his head to the discarded parka flung across the pool, sitting right at Moriarty's feet. His head tipped slightly and his lips quirked down—perhaps he hadn't considered this retort? John wondered vaguely, his heart rocketing faster than it ever had in Afghanistan. The inevitability of death in order to stop this one-man terrorist, a much greater evil…

Then his eyes flickered to the glimmering water.

A/N: Cliffhanger! Special guest appearance by Colonel Sebastian Moran (did you catch it?) and most of the lines from the second half belong to Mark Gatiss, not me ;p