Set during: A Study in Pink
"What, so you set up a pretend drugs bust to bully me?" Sherlock is furious, but when he turns to face Lestrade there is so much more emotion in his expression. Hurt. Hurt that this man would think this of him, think that he had sunk back down to his lowest point when he was really at his highest.
Lestrade meets his stare evenly. "Well, it stops being pretend if we find anything."
Sherlock glares at him. The two man stare at each other, years of memories crackling in the air between them-Sherlock hospitalized, Sherlock unconscious on the floor of the flat, cheek bones hollow, his sunken eyes. Sherlock sweating and screaming as hallucinations tear at his mind. Sherlock more bitter and angry and unsociable than John would ever see him.
"I am clean," Sherlock snaps at last, turning away.
"Is your flat?" In Lestrade's voice there is an echo of a worried parent, a person who had asked this many times. "All of it?"
The detective rolls his eyes, throws up his hands, spins around to face the other man and yanks up his sleeve. "I don't even smoke." His voice is a bitter snarl.
"Neither do I," Lestrade says, and rolls up his own sleeve, revealing the nicotine patches. "So we're in this together."
Sherlock flashes him a look of irritation, but even he can sense the meaning behind those words.
We're in this together.
Because it had always been Lestrade who had found him at his lowest point, always Lestrade who pulled him off of street corners and into a hospital. Lestrade who let him in on cases. Lestrade who quit smoking because Sherlock did. Lestrade who had Mycroft on speed dial in case of emergencies.
Lestrade, who knew exactly the right time to say, "We found Rachel."
The tension and the echo of old memories fade away and Sherlock is back on the case. "Who is she?" he demands.
Lestrade's slight smile as he says, "Her only daughter," is meant for him.
Because, even if Lestrade can drive him insane, even if he is sometimes like an overprotective parent, even if sometimes he points out things so obvious that Sherlock wants to smack him, they always have gotten each other through the difficult things.
And in the end, that's all that really matters.