Sherlock has been clean for a month. One short month. One long, excrucuation month. He's working his first official/unofficial case with Greg Lestrade. It's a murder. The victim was found in an alley: female, early twenties, working two jobs to make ends meet, no criminal record. Every friend, relative and colleague they've interviewed says the same thing - she was such a nice girl, everyone loved her. That idiot, Anderson, thinks it was a random killing. Sherlock's knows it's not.
The detective finds himself talking to an acquaintance, Joey. The young man is homeless and living on the streets.
It had been during Sherlock's darkest times that they had met. It had been a cold night and Sherlock had been too strung out to find shelter. Joey stumbled across him and guided him to a hidden alcove where he lit a small fire that provided at least a modicum of heat. That had been the beginning of an odd almost-friendship.
Sherlock thinks the killer might be hiding amongst the homeless. He's talking to Joey because the young man is intelligent and actually observes what it going on around him, maybe he's seen something or knows someone who has.
Another man walks up, Sherlock only knows him as Gibson. He's one of Sherlock's old dealers. A brief discussion ensues wherein the detective stoically denies needing a fix. Gibson finally smiles and backs away, hands raised in surrender, and leaves.
It's over an hour later that Sherlock's hand brushes over something in his coat pocket. He pulls it out and stares at it - a small pouch of white powder. Gibson must have slipped it into his pocket. The detective's hands start shaking with want and he closes his eyes.
He should throw it away, he should do it now, but he can't. Sherlock does manage to shove it back in his pocket. He paces, muttering to himself, telling himself he has to stay clean or Lestrade won't allow him on crime scenes. He'll be cut off.
The streets of London stretch out before him and he walks, the debate raging for hours and his hand slipping into his pocket now and then to touch the pouch. Finally, he looks up to where his feet have brought him, a small single family dwelling. Sherlock almost turns away, but he doesn't. Instead, he knocks.
A dark haired woman, late fourties, answers the door. He scowls at her. She's cheating on her husband. Normally he wouldn't care, but this is Mrs. Lestrade, so he finds himself surprisingly displeased. "I need to speak with your husband," he says as he brushes by her.
Even as she protests, Greg appears. "Jesus, Sherlock. This is my home. You can't be here. Unless someone is about to die, it can wait until morning at The Yard."
Those words are almost enough to give Sherlock the excuse he needs. He could leave and tell himself he tried, he really could and he would almost believe it. The detective doesn't do it. Wordlessly, he reaches into his pocket and draws out the packet. He holds it out to Lestrade. Long moments pass in which the DI stares at it. "I didn't buy it. It was a 'gift' from one of my old dealers. He slipped it in my pocket."
Greg's eyes soften. "And you came to me." He takes the proffered packet.
Sherlock nods, unable to speak.
It's so hard for Lestrade not to pull Sherlock into a fierce hug, but he already knows him too well to think it would be welcomed. Still, Greg is proud of him - he already feels a somewhat paternal protectiveness for the young man. "Come on," he suggests. "I'll fix you a cuppa." Sherlock shakes his head and turns preparing to leave. Greg stops him with a hand on his shoulder. "Sherlock, it was hard, I know, but you did it. Maybe it doesn't matter to you, but I'm proud."
Sherlock shoulders, which had been hunched, straighten. He nods once, almost turning around. "Thank you. It... matters." Sherlock leaves.