Warnings: Spoilers for series 2, some strong language, mild violence, blood

Disclaimer: Don't own Sherlock

John Watson was glad that there was no one in love with him when he had gone off to Afghanistan. It was one of the many trivial and slightly morbid things that had crossed his mind while he had been lying on his front in the desert, bleeding out rather rapidly from the bullet wound in his shoulder as he waited for someone to find him and take him to the nearest medical facility: at least there was no one back home who would have been going through this for him, dropping to the ground in the middle of whatever they had been doing because he, thousands of miles away, had been careless enough to get shot.

Yet, at the same time, it was disheartening to know that there was really no one out there who cared about him enough to risk taking the bullet for him. Then again, when being in love with someone put you at risk of being injured any time something happened to the object of your affection, most people were put off falling in love; love was for the brave, and those who were willing to put their beloved above all other selfish considerations. John had not yet met anyone who was willing to be so selfless for his benefit, no matter how hard he had tried.

No one was entirely sure of the reason behind such connections between individuals, even though every few months some newspaper or magazine printed a story which declared that there was some amateur scientist working out of their garden shed who had tracked down the source of this phenomenon and was either working on, or had already managed to engineer, a cure – but each one was a fake, and in reality not even the teams of scientists who had made it their lives' work to try and understand this very principle were any closer to coming up with an answer than they had been when they had begun decades before.

All anyone knew for certain was that if someone was injured by accident or by someone else, and there was someone who was in love with them, the injury would manifest itself on the body of the person who was in love with them. The same could not be said for emotional or self-inflicted injuries, but even so, there seemed to be endless contention over whether or not this phenomenon was a blessing or a curse.

Some thought that it made it so easy to realise when someone was in love with them – or when they were in love with someone else – and some women were incredibly excited at the prospect of transferring their labour pains to their significant others. The phenomenon also proved useful in the judicial system, when someone's guilt or innocence could be determined based on whether or not they were in love with someone, and a conviction could be made by injuring someone involved in the investigation – usually by giving them a papercut, because it was generally considered that anything worse would be unethical, especially if the person they were trying to catch out wasn't in love with them.

Yet others hated that falling in love put them at such a great risk of physical injury; the fear that one felt when their loved one left the house every morning to go to work, and that if anything happened to them then they would be the one experiencing the pain, was almost too much to bear. John had been unaffected by the phenomenon for over three decades before it reared its ugly head, and when it did, he found that it was anything but a blessing.

When John had first moved in with Sherlock Holmes, he thought that he had found another one for whom no one would ever take the risk of falling in love with. Not only was the man leading an unnecessarily dangerous life, but he was such a bastard that he didn't seem worth going through all the trouble of taking the fall for all of the injuries that he managed to get while in the pursuit of criminals to end the endless tirade of thoughts racing through his fast-paced mind. Not even Molly Hooper had truly fallen in love with him; her infatuation, while impossible to ignore, was still weak enough to protect her from all of the potential broken bones and bullets that she would have faced had she actually given him her heart.

John found some kind of comfort in the knowledge that he was not the only one who hadn't found anyone willing to risk injury for him; it was nice to have the solidarity, and he found that Sherlock's uncaring attitude on the matter was infectious. Yes, he still went on dates and attempted to acquire a girlfriend, but the more relationships he had – and the more relationships that failed – he realised that he just didn't mind not having someone to love and be loved by as much as he had before he had gone off to Afghanistan.

The affair with Irene Adler had concerned him. At first, he had wondered why Sherlock had put up with her – with those texts and that ringtone and all of the games she seemed to play with him. He had, at one point, feared that he had fallen in love with her, and that he would suddenly be succumbing to weird and wonderful injuries that were being inflicted on the dominatrix right, left and centre.

Then the news that the woman had been beheaded reached him, and he realised that – since Sherlock still had his head firmly fixed upon his shoulders – perhaps the detective had not been in love with her after all; or, at least, he had given up with her antics when she had faked her death over the ambiguous week between Christmas and New Year.

So time had gone on; neither of them worried about who might have fallen in love with them, or who might suffer if they were to fall off a wall or something while they were on a case. They continued to look for people who victims of murders were in love with to find the real target of the murder, and they continued to find people who had been murdered unloved, so that they died with no one to take the fall for them.

It was on a case when the latter had happened that John had experienced the phenomenon first hand.

It was a simple case – a conman who killed his marks as soon as they realised that they had been swindled – but the killer had eluded their capture for a week before they managed to track him down to a house in North London.

The chase that had ensued led them down a complicated system of alleyways which twisted and turned in a number of different directions. Usually, in a chase such as this, Sherlock was far ahead of the doctor, racing off on those bandy legs while John struggled to catch up; yet, for some reason, John had managed to overtake Sherlock this time – the detective was several alleyways behind by the time the killer pulled a gun out of his waistband and aimed it at John.

The doctor stopped in his tracks, raising his hands. He didn't wish to surrender, but he didn't want to get shot either. The killer chuckled, noting his hesitation.

"I'm guessing there's no one out there who'll get hurt if I pull this trigger, is there?" he asked, clicking the safety off of the gun and aiming the weapon at John's torso.

John said nothing for a moment, trying desperately to think of something to say that would get him out of this, hopefully with the killer in handcuffs and the back of a police car, and his own body without a bullet embedded in it somewhere painful and potentially life-threatening. He decided to go with the talking technique.

"Look, there's no point in running," he began, "cause someone will get hold of you at some point. There's a whole unit of the police looking for you tonight. What will you gain if you shoot me?"

The killer narrowed his eyes slightly and tilted his head to the side, thinking. He kept the gun pointing at John.

"Well, they'll certainly be distracted if they have to deal with a bullet wound. Not to mention the paperwork that they'll have to do if a civilian gets injured on a case. I might not get processed for a while – maybe enough time to build up a decent defence – and then I could walk off scot-free."

John opened his mouth to retort, but was cut off with the loud sound of a shot being fired. He closed his eyes instinctively, waiting for the pain to come – but it never did. He had heard stories of people not really feeling pain when it was too intense – some kind of safety feature in the brain protected them from having to deal with it – but when he had been shot before, he had definitely felt it, and it had fucking hurt, so why couldn't he feel anything now? And why was he still standing?

He opened his eyes tentatively, looking from the smoking gun in the hands of the killer to his torso, which was completely uninjured. He lifted his disbelieving his gaze to the killer.

"Well," the killer huffed, taking a step backwards, "it seems that someone loves you after all."

With that, he turned tail and ran. John made to follow him, but stopped after a few steps as he pondered the implications of what had just happened. There was only one reason why he had felt no pain, and he knew it, despite how difficult he found it to believe – someone, somewhere, was in love with him, and they were currently lying on the ground, or their kitchen floor, or their bathroom floor, or somewhere, bleeding out from a bullet wound in their abdomen. What was worse, was that John had no idea who it was, and how he could get to them to help them. He could only hope that they weren't alone, and that there was someone there with them who could get them to a hospital in time.

Off in the distance, a police officer appeared from around a corner that John couldn't see from where he was standing and tackled him to the ground. John watched the officer confiscate the gun and handcuff the killer, before a sudden horrible and numbing thought struck him.

Where's Sherlock?

John and the killer had been standing there talking for at least a minute, and there was no way that the detective could have been that far behind – he should have caught up with him by now.

Secure in the knowledge that the killer was being taken care of and he had no further duties relating to his capture, John turned on his heel and made back the way that they had come, though he only needed to turn a single corner before he found his flatmate – lying on the ground by the wall of the alleyway.

"Oh, my..." he breathed, running towards him and dropping to his knees by the detective's side.

Sherlock was dangerously pale, his breathing deep and quick as sweat dotted his brow. His eyes were open wide, filled with pain, as an awful red stain grew on his previously perfectly white shirt.

"John?" he gasped, his voice broken with pain.

"Yeah, it's me," John said, reaching forward and placing his palms over the wound in Sherlock's abdomen, applying pressure to stem the bleeding and trying to pretend that this was just another patient, not his flatmate, not his best friend, who was bleeding out under his hands, whose blood was staining his fingers.

"What happened?"" the detective gasped, wincing at the pain that shot through his torso at the pressure that was being applied.

John didn't answer at first; he used a silent moment to harbour under the delusion that this wasn't happening, and that it certainly wasn't his fault, and that the only reason that this could be happening in the first place couldn't possibly be true, because how could he have been so uncaring not to notice if it was?

"I got shot," he answered simply, as he reached into his pocket to retrieve his phone and ring an ambulance.

"Oh," Sherlock said simply, and a faint pink hue tinged at his cheeks, as though his body wanted to blush but there was far too much blood gushing from the bullet wound to allow him to do so. "I'm sorry."

"No," John snapped as he finished the call. "Don't you dare apologise. Don't you ever apologise for this. There's only one thing that I want you to do right now, and that is not die. Okay, Sherlock? Do – not – die."

Sherlock nodded, his eyes beginning to slip closed. "Okay," he whispered, "Okay..."