Sherlock was five years old when he first learnt of the soulmates. He'd been studying the different types of biota in their back garden when he felt it. A sharp yet dull pain on the cap of his right knee. He looked down curiously. There was no blood, but Sherlock felt as though he was bleeding, and had ran immediately to his Mummy who was reading a large book on the kitchen stool.

"Sherlock?" she had asked curiously, folding down the corner of the page she was on and closing the novel gently.

"Why does my knee hurt?" he questioned bluntly, hiking up his tailored shorts to show her the unmarred leg.

His Mummy had paused for a moment, studying his knee for just a second before a wide smile broke out. A shining grin which contrasted against the gentle wrinkles which had begun to appear. "It's your soulmate, Sher."

He hadn't really understood the significance of her words at the time, and had merely nodded in vague acceptance. "Okay." And then he was back outside, flipping out his Mummy's magnifying glass and jotting down the differences between the soil by the house and the soil by the well.

It was only when Sherlock started school that the word soulmate began to have any meaning whatsoever. He'd watch with scornful eyes as girls and boys would sit in circles, taking turns slapping their legs to see if any others would share their pain. Sherlock thought they were fools. Harming themselves in search for something that would give them nothing.

Because what did soulmates really give? Companionship? Fulfilment? Love? Sherlock didn't care for any of them. They were superfluous. A distraction. A pain in the neck. Sherlock was tired of feeling unexplainable bouts of pain when he was least expecting it. His Mummy had told him it was empathy. He thought it was masochism.

He felt this way until he was fifteen, when all of a sudden the pain in his abdomen became so bad he felt the urge to vomit. He recognised the feeling. It was the feeling of being beaten and bashed, until your eyes are hazy and you can't tell your left foot from your right. He recognised it because it was a familiar one. And Sherlock suddenly realised that although feeling the pain of his soulmate was often a nuisance, they could feel his pain too.

Sherlock made the effort from then on to sprint as fast as he could away from his tormentors. He ignored the upturn of his lips which accompanied his face when he did so.

John had always known about soulmates. He'd learnt about them at some point, of course, but his memories of the occasion were vague, and his early childhood had blurred into one elongated event. Nonetheless, soulmates had always been there, and John was already in love with his. While some hated the pain, John looked forward to it. It made John feel like he knew his soulmate, even if just a little.

At least that's what John told himself until he turned fourteen. From then, it seemed as though at least once a week his limbs were on fire, constant bursts of pain littering every inch of his skin. He'd walk home from school with tears welling in his eyes, flinching and jolting until he finally reached his front door step, when the pain would abruptly drop to a dull thrum. He should have been angry. He should have despised his soulmate for condemning him to such pain. But instead, John hurt. He hurt so badly, because he knew that somewhere in the world, there was a person suffering. His soulmate was suffering, but John couldn't do anything to help. That pain hurt more than any physical pain ever could.

Perhaps it was that desire to help people which led John to pursuing his medical degree. Day by day, John would study until his eyes drooped and he had no other option than to sleep. He studied with the hope that perhaps one day, he'd finally be able to heal his soulmate's wounds. John graduated university with high marks – perhaps not as high as he would have liked, but high enough. His residency at Barts had provided him with a position in the A&E department several years later, and in spite of not having found his soulmate yet, John was happy.

Sherlock soon found that living was boring. At fourteen he was smoking joints and at eighteen he was injecting himself with a seven percent cocaine solution, simply to escape the dull routine of existence. Cold cases found on the internet were repetitive, and when Sherlock had attempted to contact the police regarding current cases, they simply turned him down. Nobody wanted to listen to a school boy's opinion on murder, no matter how plausible his deductions were.

The drugs had initially been a pass time. An innocent recreational hobby that he partook in when bored. But soon enough they had led him to the wrong crowds, seeking – no, craving – something more. Mycroft knew what was going on. Of course he did. He could see his young brother wasting away, yet only observed with furrowed brows.

But then Sherlock had stopped attending university, and soon after, stopped returning home.

Mycroft had found him four days later, curled up outside Southwark Station.

"You keep this up, Sherlock, and I'll kick you out of home permanently."

Sherlock stared. "You don't live there, it's not your home."

"I'm putting a stop on your payments until you clean yourself up." Mycroft continued, ignoring Sherlock's words.

Met with silence, Mycroft could only huff in exasperation before moving to leave.

"It was the sister." Sherlock spoke finally, and Mycroft whipped his head around to stare at his younger brother. "The police are investigating who pushed Peter Gibbons onto the train tracks. It was his sister." Sherlock's face twisted into a grim smile. Mycroft scrutinised him for a short moment before turning away, swinging his umbrella back and forth as his footsteps became quieter and quieter. Sherlock was alone.

Three weeks later, Sherlock was on a different side of London, deteriorating in a drug den. Mycroft had cut off his funds four days prior, leaving him with limited cash and a constant thrum in his head. Part of him was ashamed, but the days were blurring together, and one thought remained at the forefront of Sherlock's mind:

At least I'm not bored.

And then Mycroft was back – this time with company. Detective Inspector Lestrade, Mycroft had introduced him as. He was giving Sherlock a case.

Sherlock was returned home within the day, monitored closely by one of Mycroft's associates as the week went by. At nineteen, Sherlock was experiencing withdrawal symptoms for the first time. It briefly crossed his mind that his soulmate might be too, but there was a double murder and, well…

He had priorities.

When Sherlock was twenty four, he began to dwell on the idea of soulmates. Though he didn't care to find them, and was perfectly content with his studies, his mind palace would continue to taunt him with a stark nothingness in its far left corner. An unknown face with an unknown name and an unknown background. He still despised the thought of them, and his frustration only built when Molly Hooper began purposefully knocking her arm on bench corners and falling over at the slightest touch.

"I'm not quite sure your soulmate would appreciate that, Molly."

The girl in question had stiffened, though a spark of hope glimmered in her eyes as she stared at Sherlock. "W-Why? Are you in pain?"

Sherlock's eyes remained on his microscope, disinterested. "Hm? Me? Oh, no. My soulmate is rather… careful."

"Oh…" Molly had spoken, her voice a whisper. "Right then."

The nothingness became too much, and months later, Sherlock had relapsed. It was morphine this time, and was much easier to obtain due to his connections at Barts. Sherlock had always prided himself on not letting himself be consumed by the chemical defect that is 'love'. And he didn't. He wasn't.

The fact that this unknown being – this soulmate – was in control of so many of his thoughts infuriated him. He vaguely wondered how Mycroft did it. Remained so unattached. So cold, one might argue. Sherlock remembered a story his older brother had told him when he was young.

"All hearts are broken. All lives end. Caring is not an advantage, Sherlock. Imagine the pain one must experience when their soulmate is dying – no, dead. Physical pain is one thing, yes, but I'm talking about emotional pain, dear brother. Did Mummy ever tell you about our grandparents?"

"No."

Mycroft had smiled grimly. "Our grandfather was shot in the heart. Grandmother must have been in so much pain. She probably felt like she was having a heart attack, or dying. But Sherlock, can you imagine how it must have felt to feel so much pain all at once, only to feel nothing at all within the next few seconds? Grandfather died. Grandmother had known at once, of course, but the knowledge that she could never see him again gave her the greatest pain of all."

"What happened to our grandmother?" Sherlock had asked, genuinely curious.

"She died, several weeks later. Of heartbreak. Can't you see Sherlock? Attachment gets us nowhere. If she had never grown to love our grandfather, or know him, than she wouldn't have been so pained to know that he was gone."

Sherlock was already attached to his soulmate – he knew it. Somewhere, in the depths of his mind, he was attached to a person who he didn't even know yet. And the morphine, that glorious temptation, was the only thing that took that attachment away.

One year into his deployment in Afghanistan, John awoke in the dead of night with a strong pain in his abdomen and the irrefutable need to vomit. But upon kneeling by the communal toilet and sticking his fingers down his throat, release would not come so easily, and he was left shivering on the bathroom tiles. Repetitive scratches of pain littered his arms as though someone was trying to tear his skin off, and John had to hold them close just to stop them shaking. Every limb ached, but John hadn't exercised any time recently, and hangovers were a thing of the past.

Realisation dawned on John like a wave – engulfing him completely and leaving him shivering with shock. Although nobody was trying to tear his skin off, and although he couldn't vomit, someone in the world – his soulmate – was experiencing this agony firsthand.

When the tremors and aches didn't stop after one night, John could only come to one conclusion. He'd seen it many times in patients back at the hospital, of course, and it never got easier. Drug withdrawals. And judging by his soulmate's symptoms – opioids. By day four, the pains were driving John mad, and the only thing which kept him sane was the knowledge that his soulmate was experiencing this too in an effort to better themselves.

John vowed to stay strong and be ready to hold his broken soulmate in his arms when they finally met.

If they finally met.

Because three days later, when the withdrawal symptoms had stopped completely, John stopped experiencing any pain. At all. Weeks passed, and there were no more occasional jabs on his hands and wrists. John should have been relieved. After all, here was a sign that his soulmate was no longer abusing substances. But the lack of pain was odd – eerie, even – and it left John with a human sized hole in his heart.

When a month had passed with no sign of any pain, John had lost all hope. His soulmate was dead. Maybe an overdose. Maybe a murder. Either way, his soulmate was gone, and with them, John's reason to continue. Having already joined the Fifth Northumberland Fusiliers, John decided to simply let his life play out, putting all his effort into training and healing his fellow soldiers. He was good at it, and he genuinely enjoyed it. Soon, he found himself being promoted to Captain. He wasn't as happy as he should have been.

One year turned into two, and while John could have sworn he felt occasional bouts of pain, they weren't obvious enough to be attributed to his soulmate. Slowly but certainly, he was falling into a depression so deep, John was uncertain he'd ever be able to rise above it again.

And then there was an attack on their base, and all troops had been called to action. John remembered feeling distant, as though this raid was a small obstacle one might face every day. His focus was marginal, and he took cover and shots at the enemy with the familiarity of routine. He vaguely recalled shouting – desperate yells – before a familiar singe littered his hands. John might have fallen over, if he weren't already crouched. He stared at his hands with wide eyes, heart beating radically in his chest. They were there. His soulmate was alive and —

"John!"

Silence.

After a three month rehab program funded by none other than Mycroft, and a following six month ban on both the Barts' labs and his own personal experiments, Sherlock was bored witless.

"You need to learn how to cope with being bored without the substance abuse, Sherlock."

"You're being ridiculous, I'm not an addict."

Mycroft scoffed haughtily. "I think you'll find, Sherlock, that you are in fact what they call: an addict."

His rehabilitation and abstention had been one of the hardest experiences of Sherlock's life, so when he was finally allowed to return to his usual experiments and crime solving, Sherlock was on cloud nine.

Perhaps he'd become a little too overexcited at the prospect, because upon lighting his first Bunsen burner to record the burning time of different types of paper, Sherlock had immediately singed two fingers. He huffed indignantly, blowing on the burn before returning his gaze to the microscope before him.

That was as far as the experiment went.

Because within the next four seconds, Sherlock was collapsed on the kitchen tiles in agony. His shoulder burnt something fierce, as though the skin was being ripped apart, and Sherlock couldn't prevent the tears leaking from his tightly scrunched eyes. Curled up in a tight ball on the cold, harsh tiles, Sherlock cried. He wanted to scream. Yell for help. But the pain was too much, and he could only clutch his shoulder so tightly that the knuckles turned white. No blood seeped through his shirt and upon tedious inspection, Sherlock found no wound.

Involuntarily, he felt more tears fall and broken sobs escaped his lips. It was no longer due to the physical pain.

For the first time in his life, Sherlock was scared for his soulmate.

Scared for his life.

That was how Lestrade had found him one hour later. He'd given the door a rapt knock before entering, calling Sherlock's name with the usual urgency. "Sherlock, I've got a case for you – a triple homicide!"

No reply came and Lestrade continued to the kitchen, calling again. He paused and listened and frowned at the unnerving silence. Impatience brimming, Lestrade turned the corner and moved to yell one more time, but stilled immediately at the sight before him. Sherlock was lying on the floor, body shaking as his hands gripped at his arms like a vice. His nails left half-moon dents in the skin, and Lestrade could vaguely make out the dried tear tracks which stained Sherlock's cheeks.

"Sherlock!" Lestrade rushed forward, dread seeping through his veins. His eyes darted around desperately searching for anything recreational, though papers, half full beakers, an abundance of petri dishes, and a flickering Bunsen burner were all he could find. His features contorted in confusion, hesitantly reaching a hand out to the consulting detective.

"Sherlock? Have you taken anything? Please, Sherlock, talk to me. I need to know."

Sherlock quivered, head moving indistinctively.

Lestrade was becoming desperate and shook Sherlock's lithe frame. "Please, Sherlock."

"No," Sherlock choked out, eyes clenching. "No."

"Tell me what's wrong, Sherlock. I can't help you if I don't know." Lestrade pulled his phone out of his pocket, hurriedly composing a text to Mycroft as he prompted Sherlock's response.

Sherlock's eyes opened and Lestrade reeled at the influx of emotions presented in them. It was so unlike Sherlock to display any part of himself so willingly, and he almost felt guilty witnessing it. His hands weakly gestured to his left shoulder, the tremor in them too strong to do much else.

Lestrade, despite the underlying awkwardness of the situation, moved to inspect Sherlock's shoulder. He unbuttoned the first two buttons of his shirt, sliding the fabric out the way to gauge a better look.

The skin was clear. Completely unmarred. And he shouldn't have been, but he was surprised. Because if there was no wound, then that meant Sherlock had a soulmate. Lestrade flushed with shame. He'd always naturally assumed that Sherlock didn't have one. Which wasn't completely unjustified, really. Sherlock had never mentioned them – in fact, he was more distanced from social interaction and sentiment than anyone else Lestrade had met.

'Mycroft.' His brain supplied, and Lestrade willed it to shut up.

Maybe it wasn't the fact that Sherlock had a soulmate that was so surprising. Rather, it was the fact that Sherlock looked so broken experiencing the other's pain. Emotionally drained and helpless. Lestrade understood the feeling completely. Instinctively, Lestrade lifted Sherlock into a sitting position and pulled him tightly to his chest.

"They're going to be fine, Sherlock. They're going to be fine."

Sherlock, in his weak and shattered state, slumped against Lestrade. "'t hurts so much."

"I know."

"They're in so much pain. They're suffering." He whispered.

"I know. But if they're still in pain, they're still alive, Sherlock. They're going to be okay."

Lestrade never did get around to telling Sherlock about the case.