A.N.: So, I wrote this for a friend, who's a massive Mystrade shipper. We were talking about how Mystrade could possibly be canon while we were revising, and I just... decided to write it.

A.N.2: Just for this chapter, I would like to thank Ariane De Vere for her transcript of ASiP, it was a real help.

Warnings: Reference to a triple murder, references to drugs

Disclaimer: Don't own Sherlock

Chapter 1 – In Which a Detective Inspector Meets Two Brothers

Greg Lestrade was having a bad day.

It was only nine in the morning when he was called to a triple murder, which, after twelve hours, no one seemed to be able to gain any leads on. Three bodies had been found under a motorway bridge; obviously put there by the same person, and with times of death that were separated only by seconds, but each of the victims had been killed in completely different ways. None of the victims seemed to have any connections other than the fact that they had been in the wrong place at the wrong time. Forensics had found no fingerprints, or fibres, or anything that could lead them to the identity of the killer.

Not only that, but about half an hour after he had got there, a young junkie had ducked beneath the police tape, seemingly unnoticed, and was determined to 'help'.

The young man was incredibly thin, his sternum visible as it poked out of his pale, ghostly skin. If Donovan hadn't acknowledged the presence of the young man, Greg would have been convinced that he had seen a ghost. His obvious malnourishment was also coupled with his rather impressive height: he had to be six foot at least, and looked as though he was ready to keel over at any minute if he didn't get some food in him, and quickly.

He wore a long dark coat that seemed to hang off of his thin shoulders, and his pallid face was marred with dark circles under his glazed-over eyes; it was a look that Greg had seen so many times before: whoever this man was, he was high. Yet he didn't seem to be tripping, so Greg guessed that it was some kind of stimulant – maybe cocaine.

Greg had tried to get the man off of the scene, but had failed on his own and had to get two other officers to grab him by the arms and physically drag him underneath the tape. He was halfway to the yellow line when the young man shouted out a series of facts – he called them 'deductions' – that, he claimed, would lead them to the killer.

Utterly exasperated, but intrigued, he had called for the officers to bring the man back.

"How do you know all that?" he had asked the man, looking into his thin face and, for some reason, marvelling at his rather impressive cheekbones.

"Observation," the man had shrugged, and then went off on a long rant about how he knew that all three victims had, in fact, one single connection: they had all bought a grandé latte combo from a nearby independent coffee shop within the last few days, and they had all sat on the same park bench to drink the coffee, albeit at different times. The woman with the blue coat had been sitting on the bench at three o' clock, the man with the smoker's teeth had been sitting on the bench at four fourteen, and the final victim – a man wearing lycra who apparently wasn't a cyclist, but was only wearing the outfit because he was going on the exercise bike at his gym and wanted to 'look the part' – had been sitting on the bench at half past five.

"It's probably someone who works at the coffee shop and lives near the park, as the coffee shop itself is nowhere near the park," he had finished, a smug look of arrogance plastered on his sickly face.

"Who are you?" Greg had asked, half in awe, half in frustration and tiredness.

The man had smirked. "Sherlock Holmes."

Greg had ordered a background check immediately, and found that the man was, indeed, a cocaine addict who had studied chemistry at Cambridge and was rather famous for his party trick of telling people's life stories from the most insignificant details. From what the people doing the background check could tell, he was not generally liked, precisely for this strange but remarkable ability. Yet Greg learned one more thing about Sherlock Holmes that day, something that was not from the background check: Sherlock Holmes had been completely right about everything he had said at the crime scene.

They had gone to the coffee shop that Holmes had told them the killer worked at, and found that one of their employees did, indeed, live near to the park where the bench was. Holmes had insisted on accompanying them to the coffee shop, where he practically ambushed the man with a long stream of deductions, after which the man confessed immediately.

None of the police officers present, including Greg, was entirely sure whether such a confession was legitimate, but evidence that had been gathered from the scene, the park and the coffee shop later that afternoon seemed to suggest that Holmes had caught the right person.

However, because of Holmes' interference, Greg now had to fill out much more paperwork than he would normally have to, and the thought of all of that waiting for him on his desk at Scotland Yard was not a prospect that he particularly looked forward to.

He almost felt relieved when his phone went off unexpectedly as he watched two officers walk the cuffed murderer to the squad car. Only one person rang his mobile, and what with the triple murder, the Holmes boy and the paperwork, hearing his wife's voice would be just what he needed.

Except it wasn't his wife on the end of the phone.

He didn't know who it was, only that the man on the other end sounded incredibly important and incredibly demanding. Greg could tell that, whoever this man was, he was used to getting what he wanted.

What Greg didn't understand was what this man would want with him.

"There's a car around the corner from where you are standing," the man informed him. "I am waiting."

Greg wondered if he should be worried. After all, it wasn't every day that you got a phone call from an unknown person who ordered you to get into a car – which, when he got round the corner, he saw was unmarked and had tinted windows so that he couldn't see inside. Nevertheless, he was far too tired to deal with whatever consequence he would have to face from Scary Phone Man if he didn't do what he asked, so he got into the car anyway.

He was greeted – briefly – by a rather stunning woman who only looked up from her phone to say, "Good afternoon, Detective Inspector".

He tried, in vain, to make conversation with the woman, but she kept up her stony silence and eventually he gave up.

The car drove for about half an hour, and pulled up inside a large warehouse, just inside the entrance. The door opened and a silent man wearing a suit was standing there, holding the car door open for him. The woman who had been sitting next to him had already got out, so Greg followed suit.

The warehouse was possibly the largest that Greg had ever seen – once he could see it properly, he began to doubt whether or not it was actually an aircraft hangar, although there was no aircraft in sight.

It was perhaps due to the massive size of the warehouse that the sight of the single man standing some twenty feet away from him, on his own, leaning against an admittedly rather gorgeous umbrella was slightly comical.

Even so, Greg didn't laugh.

"Good evening, Detective Inspector," the man smiled, the same man who had spoken to him on the phone.

"Good evening," he replied slowly. "I'm sorry, who are you?"

The man chuckled, a low sound that infuriated Greg to his very core. "I am the closest thing Sherlock Holmes has to a friend."

Greg sighed. He should have known that that junkie was more trouble than he was worth. Then again, he had caught a killer the police might not have been able to find for months in a matter of a few hours… But kidnapper friends? This was really a bad day.

"The closest thing?" he asked. "And what would that be?"

"An enemy," the man explained, standing up so that he was no longer leaning on his umbrella. "Tell me, Detective Inspector, do you plan to continue your association with Sherlock Holmes?"

That, Greg didn't know the answer to. He had only known the man for a few hours, but in that time the man had proved himself rather worthy of having around. That was, if his constant presence around crime scenes didn't land Greg with even more paperwork, or kidnapped.

"If you're his enemy, why do you care if I want to spend time with him?" Greg asked, starting to feel as though he'd rather be at his desk at Scotland Yard doing the mountain of paperwork that was no doubt awaiting him.

"I worry about him," the man assured him, "constantly."

Greg huffed indignantly. "Enough to kidnap people? You do realise I'm a police officer?"

The man chuckled again. After the day that he'd had, it was all Greg could do not to punch him in the face.

"Of course I know that you're a police officer, Detective Inspector. I know that you're in your early forties, I know that you've been married for twenty years and that you have two children who have both left for university already – twins, am I correct? But they didn't go to the same institution of higher education. No, only one of them got into Oxford, the other had to go to a… less prestigious university. But they are both studying the same thing: criminology. Perhaps they want to become police officers as well…

"I know that your wife is not entirely faithful, she never has been; she cheated on you twice when you were engaged, and yet you still married her? Why is that? Maybe you needed the money, after all, she is a higher class than you and earns considerably more. Maybe it was love – true love that forgave all her past sins, but now you regret your decision. Not consciously, no, and you would never regret having your children by her, but on some level a part of you longs to get away.

"Tell me, did I get anything wrong?"

Greg was stunned into silence. The man standing before him – who, after that speech, had begun to sound an awful lot like Sherlock Holmes – had got absolutely nothing wrong, and that was slightly unnerving.

"Look, how did you know all that? Have you put a bug on my phone? Have you been tailing me? What is going on?" Greg turned to the woman who had sat next to him in the car, who was standing a few feet to his right and a few feet behind him. She was still staring at her phone, her fingers still moving across the keys at the same speed that they had been before. What on earth was she doing on there that required such fast, persistent typing and would last this long?

Sensing that he wasn't going to get an answer from her, he turned back to Scary Phone Man.

"Relax, Detective Inspector, I have not been 'tailing' you," the man rolled his eyes, "I didn't know about you until a few hours ago, when my brother was so insistent on making your… acquaintance."

Greg blanched. "Your brother?"

The man's lips became a thin, angry line. Perhaps he was angry at himself for revealing that piece of information, but he seemed like the kind of man that never made mistakes and did everything for a calculated, pre-determined reason.

"Indeed. Sherlock Holmes is my brother, and he seems to have taken an interest in you; specifically, your work.

"As I assume you know, for it is blatantly obvious even to the most doltish of minds, he has fallen into drug use – something for which I partly blame myself – and has taken to washing away his brilliant mind with seven per cent solutions. When I heard that he had solved a most confusing murder in less than three hours, when the same case had baffled professionals for more than thrice as long as that already, I must confess that I was… glad, that he was using his brain for something other than getting deals on cocaine.

"He has spent the last three years in a stupor, getting by with nothing but his own wits and fuelled by substances. All passion had left him, and he cared for nothing but getting his next fix. Today, I observed a change in him. He was no longer merely a shadow of his former self, he was his former self – admittedly still hampered by the last thing that he had injected into his veins. It is a self that I have missed, and would like to see him return to fully.

"Now, I ask again: do you plan to continue your association with Sherlock Holmes?"

Greg was stunned into silence. He had known from the moment that he had met Holmes that he was brilliant, a great man. Even so, he had not seemed like a good one, but, based on what Scary Phone Man had told him, he was inclined to blame that on to the drugs that he had somehow got into. At first, Greg had wondered if it had been the drugs that had given him this ability to deduce and reason at such an advanced capability. Now, he found out that he could, in fact, do it in spite of the drugs.

Yes, Sherlock Holmes was perhaps the most annoying man Greg had ever met, and he was almost ninety per cent responsible for the bad day that he was having. But he was also a man who needed help, and who could help him in return. He had solved a murder and caught a murderer who could have gone on to take more lives.

All in all, that wasn't a bad feat for a junkie who had a kidnapper for a brother.

"Yes," he answered Scary Phone Man, with a determined nod. "He was good at the scene today, although his personal skills with the coffee shop workers left a little to be desired-"

This prompted a small chuckle from Scary Phone Man – not one that grated on Greg's nerves like the previous ones had, but a soft, nostalgic chuckle that told of fond memories of times gone by.

"-but… I like him. He needs to get clean-"

"Undoubtedly," Scary Phone Man agreed, with a small nod.

"-but when he does… yeah, I'd take him on more cases."

It seemed like such a snap decision, especially when it was one that could possibly change his life forever – for who knows how different his work would become if he began to regularly allow Holmes to… well, what exactly would he be allowing him to do? Consult? In any other situation, he would have taken more time than this to carefully consider whether or not to use his time to the advantage of a junkie.

Yet it would not only be to Holmes' advantage, and Greg seriously believed that he could get clean. Maybe it was wishful thinking, but Greg was a stubborn man, and even if he had to drag Holmes kicking and screaming through withdrawal, the man would get clean.

Scary Phone Man smiled, a more genuine smile that almost didn't reach his eyes. It wasn't as though he was insincere about the smile, but more as though he merely didn't do it often enough to know how to do it properly.

"That's what I'd hoped you would say," he said. "But I do have one thing to ask of you, in light of your decision."

"What?"

The man shifted, almost awkwardly, then met Greg's eyes with a strange, almost desperate expression. "Look after him."

Greg didn't know either of the men he had met that day particularly well; not Holmes, nor Scary Phone Man. He didn't know exactly what their relationship was, and he certainly didn't have the same powers of observation that either of them seemed to possess.

Yet he did know that the man in front of him was determined for his brother to get better, to return to the bright flame that he had been before his descent into drugs. And if Holmes could solve a murder so quickly when he was high as a kite, then how much more brilliant a man would he be when sober?

Greg didn't know, but he did know that that was a man he would much like to have the privilege of meeting.

He nodded at Scary Phone Man in agreement, and left the warehouse in the car, with the silent typing woman, feeling as though maybe this hadn't been such a bad day as he had originally thought.