Sherlock lay on the couch staring up at the ceiling, motionless, emotionless, practically a dead body. He felt nothing, he was a numb, yet it felt like a weight had been placed upon him, weighing him down and, and pressing up against him, on his chest, causing him to breathe heavily in desperation. Behind him he could hear the faint sound of melancholy music, emanating out of the thin wall that divided his flat and that of his neighbour. His neighbour was a lonely woman by the name of Sarah who often played mellow music in the evenings. The Smiths, Radiohead, Elliot Smith, that sort of thing. Sherlock knew nothing about music, and had never shown an interest in it, yet he often felt himself enjoying those melancholy tunes that he heard in the evening. They resonated with him deeply, especially in times like these when he felt nothing. Nothing but self-loathing and a profound sense of loneliness.
It was his fault, he was the only one to blame for how he felt right now. He had grown increasingly depressed, and had pushed away everyone he cared about. The depression had come unexpectedly after a particularly difficult case that Sherlock had failed to complete, concerning the kidnappings of 3 children in east London. During that time, his friendship with John had become even more strained, as Sherlock had isolated himself in order to finish the case. Sherlock also hid himself away in order to lessen the pain he felt whenever he saw John with Mary. It was ridiculous, because they were now married and happily living together. But Sherlock couldn't accept it, he couldn't accept the fact that John was happy and needed him no more. So they drifted apart, and the loneliness mixed with the disappointment and anguish that Sherlock felt upon failing to solve the case, lead Sherlock into a deep and dark hole of depression.
Mycroft had of course noted the shift in Sherlock's behaviour, and had put Sherlock in even stricter scrutiny, so that a drug relapse wouldn't occur. Sherlock could have worked around Mycroft's strict controls and scrutiny but he didn't have the energy left in him to protest, and to cause an argument. So without drugs to cope, and without a case to solve, Sherlock began to develop a deep sense of self-loathing. Self-loathing that he had managed to bury deep within himself. It was unbearable at times, and often paralyzing. However, one summer evening, while lying on the couch with a cigarette in his hand, Sherlock decided to try something. He pressed the cigarette into his forearm, and held it there till the pain overcame him and filled him with a strange sense of relief and peace. In those five seconds that he felt the burn of the cigarette, he felt peace,, he felt his self-loathing ease away. He smiled to himself and relaxed. It was juvenile and stupid but he had found a method to ease the pain. The next day he found himself doing it again. It was like an addiction, because since that day Sherlock hasn't stopped.
Sherlock missed John in these moments. John would care, he would understand, and most importantly he would notice. John had the extraordinary ability to look beyond Sherlock's callous exterior. No one else could do this, well no one other than perhaps Mycroft. But Mycroft was different, he was Sherlock's brother, so of course he'd understand. Sherlock knew that John would reach out in order to help immediately, if saw that anything was wrong, because John knew that although Sherlock presented himself as cold hearted, uncaring, and arrogant, it was all an act. It was all an act, in order to mask the feelings of inadequacy and self-loathing that Sherlock felt. John had recognised this in Sherlock from the start. He saw a broken, intelligent man instead of the arrogant, self-righteous, genius that everyone saw.
Sherlock continued to lie on the couch, with his eyes fixed on the ceiling when a sudden knock on the door broke his trance. From behind the door he heard Mrs. Hudson saying the words "Sherlock you've got a package, a big brown box, I can't lift it up…." Sherlock was forced to get up and open the door. He opened it to find Mrs. Hudson sitting on the staircase, panting and complaining about the heaviness of the box she had carried up for him. He picked up the box, mumbled a quick thank you, and shut the door angrily.