Sherlock doesn't normally have nightmares. Nightmares are emotional things, after all, and as a man who rejects emotion in all (most) of its forms, he simply has no use for them.
Until the pool. Until Moriarty threatens to burn his heart out. Then the nightmare comes.
It starts like any other day (strange, Sherlock despises normality, but they'd developed a routine and he likes it). He joins John in the kitchen in the morning, eschewing the toast his flatmate offers in favor of the day's paper and a cup of tea. Sometimes Sherlock accepts, to see John smile; not today. There is something off, something niggling, Sherlock can't put his finger on it. Then John finishes eating and turns to him.
"I got you a present, Sherlock."
An eyebrow rises, and the paper is set aside. This is new. It isn't Sherlock's birthday- not that John knows when that is- or any other holiday he can recall. And Sherlock is particularly difficult to buy for, according to Mycroft. But John knows him so well (better than Sherlock could ever have imagined he would), so perhaps it is a present worth having.
John holds out a small box, wrapped in simple brown paper. Roughly ten centimeters on a side, eight centimeters in depth. Sherlock takes it and weighs it in his hand. Twelve ounces. The bottom of the box is damp, even through the wrapping, and it smells faintly of blood. Something for his experiments, then. John can be very thoughtful at times- Sherlock will have to use this one for something special.
"Well? Open it." Odd. John's voice sounds odd. Flat. Sherlock will study him carefully in a moment, once he has opened his present, until he has deduced anything troubling his John and can make it go away. In a moment. The brown paper- cheap, practical- tears away, and he was right, the bottom is stained with blood. The box is just as plain, white cardboard where there is no blood, and inside is a fresh human heart.
"Thank you, John." Sherlock is surprised. He doesn't know why, or why there is an uneasy twist in his lower intestine. "Where did you obtain it? Bart's?"
"No. It's mine."
Sherlock finally looks up at his flatmate, startled. John is smiling at him, his familiar easy smile that usually makes Sherlock feel warm and content inside, but his eyes are empty. There is blood on his white t-shirt (it's too warm inside for a jumper, so why does Sherlock feel cold?), seeping steadily through the fabric, and Sherlock reaches out. The cotton is warm and damp against his fingers (and the blood, he smells the blood now, can't smell anything else, why didn't he notice) as he pulls the hem up, until he can see the gaping wound where John's heart should be. Thick stitches had burst, looking like little black worms to either side of the red-
"Don't you like it, Sherlock? I wanted you to have it." And John's voice is empty, because of course how can he feel, John feels with his whole heart and his heart is in Sherlock's hand.
John smiles at him, like a doll, and Sherlock wakes up. His chest hurts, and his throat is tight, and his mouth is so dry it takes four tries to swallow. And he understands.
John's heart is the greatest gift in the world. There is nothing Sherlock would rather have, the cases or the praise or even the genius, than the heart of one simple man who gives all those things meaning. And so long as Sherlock is Sherlock, attracting blood and danger and mad criminal masterminds every alternate Tuesday, it is the one thing he cannot allow John to give him. Ever.
And it burns.
A/N: My first posted foray into the incredibly shiny BBC Sherlock. It was supposed to be an attempt at a 221b. After about 400 words, I figured that wasn't happening no matter how much I went back and edited out.
There are a couple of other things I'd wanted to finish and post first, but I am currently balancing thirty hours of being awake with maybe two hours of sleep, and I didn't want to lose the utterly random, creepy scene when it popped into my head. I'd appreciate if anyone with more experience with Sherlock gave positive and negative feedback before I get too deep into longer stories.
The author owns nothing pertaining to BBC Sherlock.
28 May 2011