His phone rang. Again blocked number. He swiped to answer it and slowly raised the phone to his ear.

"Sherlock!" Moran's voice was pleased. "Congratulations on winning the match last night, with a little help from your friend of course. How is Dr. Watson?"

Sherlock's eyes flashed toward his flatmate. Dizzy spell evidently passed, John was sitting up now, looking at Sherlock with concern.

Sherlock didn't speak. He couldn't.

"I thought so. Took you ages to figure it out. I'm shocked. I heard you were some sort of master of observation. But John's had the poison for—what is it?—nine days now? And you didn't notice? Really, I thought you cared about him more than that. But perhaps you don't."

Sherlock felt his fingers clench the chair's arm. It was true; he hadn't noticed. The information was there, subconsciously recorded; his mind had tried to warn him in the dream just a few days ago, lying on the living room floor, holding onto John: I'm going to have to leave soon. But the data hadn't made it through to his conscious awareness. He'd been distracted by the flooding. His emotions for John had made him miss the facts. The feelings had drowned out what was important: namely, the fact that John had—what he had confirmed himself to be—an irreversible poison running in his veins, killing him slowly.

Nine days. Sherlock's heart must have stopped, falling deadly still as the numbers clicked by in his head. Parker had died nine days after receiving the poison. Rodgers had died in fourteen. John could have up to five more days, or he could die tonight.

"The bullet was meant for you," Moran continued. "We thought it would be fitting for the poison expert to die of a poison he couldn't remedy. The final failed challenge. But it's a rather pretty twist of fate that John took it for you. Moriarty couldn't have been more pleased. This way, you get to watch the one person you"—he paused suggestively—"live with, die before we kill you. A psychological death followed by the physical one. It's perfect because I think we both know that the psychological death is far, far worse."

There was glee in Moran's voice. Sherlock couldn't move.

"We have a bet going that you'll kill yourself—finish what you started up on the roof of Barts. I think you will. Because you'll have to watch John die knowing you weren't smart enough to save him. I think that's worth killing yourself over, don't you?"

There wasn't enough air. His body was numb. His ears were ringing with the sound of Moran's voice and the deafening silence in the room. John was talking, asking him something. Sherlock couldn't hear it. The silence was too loud.

"We'll kill you anyway, if you don't kill yourself. But I think you will. Actually, if you're as self-centred as they say you are, you might even kill yourself before John dies so you don't have to see it. I'm sure it would make John very, very sad, but as we've established, you don't seem to care much about what happens to John."

"What's he saying, Boss?" Sherlock heard a voice in the background.

"Is he surprised, Boss?" the other voice wanted to know.

"Ask him to send us a reaction selfie," the first voice said.

Sherlock hung up the phone.

"Sherlock," John's voice broke through. "What's wrong? Who was that? Sherlock?"

He stood up slowly. He couldn't feel the floor beneath him. There was no air in the room. How was he breathing? He must have forgotten how to breathe. The point seemed unimportant. He walked into the kitchen in a trance. He took two small knives from the wooden block—short, steel blades—placing one in his pocket and the other behind his back.

Then he was in the living room again, in front of John. John was talking.

"This is getting a bit scary. Just say something. Who was that on the phone? Was it Moran? Moriarty? Not dead? Is he back?"

"Give me your right hand." Sherlock's voice sounded strange to his ears.

"Tell me what's going on."

Sherlock stared at him blankly. John gave up and held out his right hand. Sherlock grasped it firmly, aware of John's eyes darting to his face. He took the knife from behind his back and slashed it quickly, shallowly, across John's palm.

"Shit!" John yelled, jumping back as blood pooled in his hand. "What the motherfuck—"

Sherlock had already grabbed a clean vial from the table. He pressed it to John's hand, allowing the blood to run into it, waiting for the correct amount.

"You know, it's great when you do the whole 'waiting until the last moment to fill me in' thing, but if you're going to be cutting at me with knives and collecting my blood like a mad—"

John stopped abruptly as Sherlock flipped the other knife from his pocket and cut his own, left, hand and filled a second vial.

The method wasn't ideal, but there was no time. No time for tourniquets and careful venipuncture. Even if he wanted to do it here, the gauge of his hypodermic needles was better suited for injections than extractions, and John would insist on going to the lab to have it done properly and there wasn't time.

He labelled the vial of his own blood with shaking hands. John had moved off somewhere, which was why when Sherlock finally looked up he was startled to see John standing so close to him.

John grabbed Sherlock's left hand and before he could pull it back ran a disinfectant cloth over the cut. It stung. The doctor wrapped Sherlock's hand in gauze and Sherlock wished he were dead. Moran was right. He was self-centred. If he were dead he wouldn't have to witness this: John taking care of him, not yet knowing he was dying and that Sherlock had allowed it to happen—these last precious moments of light before the swiftly encroaching shadow.

Into the woods again. Into the dark. Like with Moriarty, when it had ended with a fall, and he was dead for two years. Like with Magnussen, when Mary killed him, and he was dead for six minutes. He wished it would be as simple as dying again, but this was different.

This was about John.

It had finally happened. Sherlock Holmes had snapped.

Gone round the bend, off his trolley, away with the fairies. He had certainly gone anyway—dashing out the door and slamming it behind him, but not before slicing John's hand and his own with knives, collecting their blood samples like a deranged serial killer.

John had barely finished dressing Sherlock's hand before the detective grabbed his arm, stepping close to him—too close, especially too close considering what happened last night—looking at him with an expression that made John's breath catch. Because it looked like goodbye and John wasn't sure if Sherlock was going to kiss him or cut his throat.

In the end he did neither. He looked like he was about to say something, but he didn't. Without a word he had turned on his heel and run out the door, forgetting his coat and scarf on the hook. Further evidence: Sherlock must be off his rocker if he could forget the beloved coat and scarf on a cold night. John had watched him jump into a cab from the window, briefly wondering whether he should call Lestrade to warn him that the mad detective had really gone mental this time and was loose in London with kitchen knives.

John went back to the window now, running his fingers over the dressing he'd just finished on his own hand. He knew his flatmate's erratic behaviour was a direct result of that phone call. He suppressed a shiver. Sherlock's expression—colour drained from his face, eyes unblinking, shallow breathing.

Could it have been Moriarty on the phone? Sherlock had said he was dead; no question. Maybe it had only been Moran. But what could he have said to make him react like that? John had seen Sherlock talk to Moriarty before. The consulting detective was invariably snide and detached in the face of criminal masterminds. But this time he hadn't said anything at all. And his expression… Could it really have been fear?

John crossed from the window to sit down in his chair. He would have to think like Sherlock if he was going to figure this one out.

Assuming Sherlock hadn't spontaneously gone violently insane (still not a possibility to entirely rule out), there was a logical reason why he needed samples of their blood. He would be testing them for something. Had Moran injected Sherlock with more than just heroin last night? John felt his throat constrict, suddenly aware of the effort involved in both breathing and swallowing.

That must be it, mustn't it? The poison from the Rodgers case; it was Moran's poison. It would stand to reason that if he caught Sherlock he would want to poison him, to ensure his death in case Sherlock escaped the man that had been sent to kill him last night. Moran had called him just now to inform him of it. Sherlock had gone to the lab to test his blood, and he would use John's as the control.

Oh god. John breathed hard through his nose. In, out, trying not to hyperventilate. If Sherlock was poisoned… But no… Something was off. Sherlock's expression… But of course he would look like that if Moran had just told him the poison Sherlock had himself declared to be 'genius' and 'unbeatable' was running in his own veins… John held his head in his hands. Dizzy. He couldn't breathe. Irreversible poison in Sherlock's blood—no antidote—the idea ripped through him like jagged metal. It hurt. No, no, no…

Dizzy, John tried to keep his thoughts from spiralling. What was it about Sherlock's expression that was bothering him? It was panic. John had seen it on Sherlock before but never when Sherlock's own death was imminent—not in the times he had faced Moriarty and never when a gun was pointed in his face. No, Sherlock didn't look like that when confronted with death. But he had seen Sherlock look like that somewhere before… When was it? John grasped for the memory.

And then he knew. He had seen that expression on Sherlock's face only twice before today. The first time he'd been standing beside a swimming pool. The second time he'd been on his back in the grass, on Guy Fawkes Night.

John breathed. Sherlock wasn't poisoned. He was.

"Billy," Sherlock barked into his phone in the back of the cab. "Meet me at the lab. Now. Bring an eight ball of coke. At least."

It was a long time since he'd had any cocaine, but he remembered the frankly dazzling speed at which his brain could work when stimulated with the drug. If nicotine was good for brainwork then cocaine was truly excellent. Short-term brainwork, of course. Sherlock also remembered the rather unpleasant crashes coming down from the high, but that was no matter now. He was not going to rest until he found an antidote. It could take days and he would need the drug to keep him going. But no, he didn't have days. John could be dead tomorrow—Sherlock's eyes slammed shut as the thought seared his brain.

In an instant he was able to clear the mess in mind palace. All damage repaired, everything put back into place: pristine. He could do it now because it was important now. He needed his brain in top form. He'd studied this poison and determined it to be irreversible. It was an impossible task and he would have to do it. There was no alternative. He would do it, because John would not die. Sherlock was the best goddamn chemist in England and the unrivalled bloody expert on poisons. He could do this. He had to.

He thought grimly that Moriarty and Moran had really outdone themselves this time. John's death would paralyse him, they knew that, but they'd taken it even one step further. Because if John died of poison, not only Sherlock's area of expertise but his point of pride— He couldn't imagine a more decisive way to destroy him. He agreed with Moran wholeheartedly on this one: If John died of a poison Sherlock couldn't save him from, he would not need to be told twice to jump off a building. No landing gear this time. No tricks. He would be more than happy to meet the pavement.

Sherlock breathed deeply through his nose as he realigned his concentration. He couldn't think about endings now. They were only distraction. Now he needed to focus on the problem. The problem and the method.

He picked up his phone again.

"Molly, I need your help. Meet me in the lab. Ten minutes."

John leaned back in his chair, exhaling slowly. The predominant feeling was relief. So he was dying, and not Sherlock. It wasn't ideal, but it was infinitely better than the other way around. Because he wouldn't do that again. He couldn't. It wasn't an option. It would shatter him completely, again, but this time there wouldn't be pieces large enough to put back together—a consequence of repeated breaking. No, it was better this way.

He'd always expected to die on a case with Sherlock. He had chosen his death when he'd chosen Sherlock. It was a simple matter of statistics. They had too many cases with too many ways to die. Too many people trying to kill them. There's a limited amount of time you can spend on a battlefield before a bullet catches you. John knew it better than anyone. Eventually it would happen. And he didn't mind. If he had to choose between dying slowly of cancer or failing organs when he was eighty or dying on the street protecting Sherlock before he turned forty, he would always choose the latter. Death was senseless if it was going to be done wasting away in a hospital bed. He wanted his death to have meaning, and the meaning he'd chosen—the best meaning the world had to offer—was dying for Sherlock Holmes.

He touched his left upper arm, tracing the cut where Carl Reeves' bullet had grazed him through his sleeve. That, he assumed, was how the poison had gotten into his system. The bullet had been aimed for Sherlock. And John had taken it for him. Perfect.

It wasn't that he wanted to die—not at all. It turned his stomach to think of all the cases he would miss out on. Sherlock would have to go alone. Or replace him (his stomach flipped over entirely). He wanted to stay at 221B, of course. Stay with Sherlock. Maybe find out if there was something between them. Or, if not, settle back into their friendship. He would miss Sherlock's voice, his laugh, his smirks and his smiles, his laziness and his energy, watching him work, watching him think, his eyes… John swallowed. No, he didn't want to die. But if he had to, he was glad it had happened like this: taking a bullet for Sherlock. He would do it again in a heartbeat if anyone gave him the choice.

After all, John thought he must have the better end of the deal. As he knew from past experience, it's much easier to die than to watch someone die. Or at least it is when that someone is a (the) person you need. A person you would spend whatever wretched remaining years you had suffocating without.

Sherlock, he supposed, had gone to the lab to try to find an antidote. Perhaps he would succeed. Perhaps he didn't have to die. But hadn't Sherlock said himself the poison's progress was unstoppable? He knew Sherlock would do everything he could, but if there was no solution then there was no solution. He had to be prepared for that. Because Sherlock had studied the poison carefully, and of all people he was the last one to declare something 'perfect' if it had even the smallest flaw. And to Sherlock this poison had been perfect.

But it would be ok, he thought, staring absently at their chaotic wallpaper. Sherlock didn't need John the way John needed Sherlock. The detective had his work, and John knew that as long as he had that he didn't need much else. Sherlock would be all right without him. He would do better, certainly, than John had done when Sherlock was dead. Mrs. Hudson would take care of him. Mycroft would watch over him. The consulting detective would be unhappy for a while (perhaps, if John flattered himself, even quite a long while—certainly longer than when Irene Adler had died, he hoped), but he would be ok, and that's what mattered.

As for himself, John had known within twenty-four hours of meeting him that Sherlock was someone he'd live for, kill for, and die for. Not everyone is lucky enough to find someone like that. And John counted himself lucky. He'd chosen to live for Sherlock at a point when he'd had nothing worth living for. He'd killed for Sherlock when he needed to, and now he could die for him as well. It was nothing more than the fulfilment of the original design.

Still he wasn't thrilled about it. John let his gaze travel over the living room, thinking that he didn't understand the concept of heaven. How could you be happy anywhere if your consulting detective isn't there with you? To play the violin or burn holes through your tables; to play Cluedo with you or toss fragile vials of dangerous chemicals at you; to help you on with your coat or follow you around the flat complaining about everything; to push you out into the night after murderers, running at your side?

John sincerely hoped there wasn't any kind of afterlife, because he knew that if even the smallest piece of him went on he wouldn't feel anything but pain for missing Sherlock.