He dreams of deserts; sand dunes burying forgotten civilizations underneath forgotten civilizations. Battlefields where the grounds are uneven and traitorous. Around him is a sea of half-buried militia; a score of bullets graze him from all sides. Shouts in foreign languages echo, like gurgles from the unknown below. Everything is set to distract him, but he won't allow it. Sherlock wants to see, has to know, what they try to hide from him, so he digs. He pries the sand apart with his hands, the sleeves of his shirt rolled until his elbows, sweat making his suit cling to him around his neck, his chest, choking him, making it hard to breathe; around his arms, restraining him, making him impatient and aware of his parched throat. He feels the sun beating down upon him, heat forcing him to collapse.
The wind comes, but instead of comfort running up his spine, it threatens to burn him, and only brings more sand. The grains invade his lungs, his eyes and the space underneath his fingernails. When he has finished rubbing his eyes, the landscapes have changed; more answers have been buried, even before he's had the chance to find them.
Sherlock continues digging, but all he unearths are sculptures of questions. Frighteningly, they all take the shape of John: John's face, the way it creases when they share a private joke upon leaving crime scenes; John's hands, the way they shake and tremble less and less as they unravel more of Moriarty's secrets; John's knee, twitching in a constant rhythm, yet refusing the comfort of the cane; John's heart, how it doesn't remind Sherlock of other hearts because this one beats a different tune; a tune in line with gunfire, an absence of fear and of pips. Always of pips, and it is this that wakes Sherlock before he can find the answers.
In the waking world, John is nothing more than a memory. Sherlock will be typing away at his laptop, tracking down Moriarty's next move, and he will hear a kettle boiling. He will raise his head but he is not in Baker Street. Sherlock will be running across highways, dodging death and he will feel a hand by his elbow, pushing him to go further. He takes a stroll down Regent Park and he will see John and he will see sand dunes; he sees John drenched in sand, tiny grains overflowing from his ears, from his mouth and the bullet wound. John scattered all over an endless horizon, teasing him with body parts, but never revealing himself whole.
Because Sherlock knows that once he finds John, everything of John, his hard drive will force him to delete everything, with no exceptions, not even the way he flung himself at the mine field of crimes Moriarty plants for Sherlock. John Watson is gone and his hard drive has no need for someone who won't be useful for the work, for the game, but Sherlock has already lost John in the physical sense. He refuses to lose him in memory as well.
Sherlock dreams of deserts. Tonight, he understands that he isn't the body desperately searching for answers; he is the sand, he is the wind, he is the sun. He is the desert preventing himself from committing the greatest crime his mind can ever act upon.