"Bored."
"Yes, Sherlock, I know."
"Bored."
"For Christ's sake, YES, Sherlock, I know."
Four weeks. Four weeks it took for Sherlock to appear again after he fell from the roof of St. Bart's. John asked for one more miracle and he got one, though Sherlock was most definitely still dead.
Pale and translucent, he appeared besides John one morning whilst he was making coffee, and laughed as John promptly spilt it all over himself.
"What's the matter, John? You look like you've seen a ghost." He said, and John's arm sailed straight through him when he swung a punch.
Sherlock, as it turned out, was just as surprised to find himself back as John was, and whilst he was clearly pleased that he was able to spend more time with John, the reality of spending an eternity as an incorporeal being with nothing to do eventually hit him hard.
Cue Sherlock temporarily becoming a moping spirit, floating about the flat aimlessly and wailing about the cruelty of the afterlife. John wondered if he'd made a mistake wishing to get Sherlock back.
It took a week or so, but John finally brought Sherlock around with some of his music. It was hard to watch the great detective try and adjust to being a ghost, just as it was hard for him to learn to live with him when he was in this state. Gone were the days when John could pass Sherlock a pen by throwing it at him, knowing he'd catch it - now it would sail right through him. Not that he had any need to write anything now he was dead.
It struck John hardest the day he returned home from work to find Sherlock hovering above his violin, fingers twitching over the strings but plucking none of them. The silence of the scene was like a ringing in John's ears. Quietly, he moved to the windowsill and drew up the violin, resting his chin against it and picking up the bow.
"John, what...? You can't play." Sherlock said, expression flicking from quiet sorrow to confusion.
"No, but you can. Help me." John replied, turning to press play on the speakers behind him. The pitched notes of Sherlock's violin filled the room - his composition, his playing, his own recording, and John watched as Sherlock's eyes lit up in recognition. John brought the bow up to the strings, and Sherlock seemed to understand. He settled down to the floor again, walking across, and lay his hands over John's until it seemed like he was holding the violin himself, hands shimmering where they went through John's. It was cold, John realised, as Sherlock held the same space he held. Cold, but unobtrusive.
And then Sherlock began to play. Not really, of course. The bow lay still against the strings, as did John's own fingers, which would never keep up with Sherlock's own if he tried to follow them, but Sherlock's fingers 'pressed' upon the strings and moved as through drawing the bow across them and the room was filled with the sound of his music, so it was the best that John could give him.
A few months and many hours of secret lessons later, John could finally play well enough to shakily follow Sherlock's lead himself, and they had no need for the recording anymore. And yes, Sherlock complained about John's amateur fingerwork and how he gripped the bow, but John caught the look of pride in his eyes when they finally played through the whole piece together with no faults, and he decided a few complaints could be forgiven.
Of course, playing the violin together could only entertain Sherlock for so long, and it was only a matter of weeks before Sherlock was looking for something else to do. He was back to floating around the flat and moaning about how boring being dead was when John finally had the bright idea to give Sherlock a challenge.
John pushed himself up from his chair and strode over to the sofa, where Sherlock was lounging a foot above the cushions, looking intolerably bored. With firm finality, John set down a pen on the coffee table.
"What are you doing?" Sherlock asked, eyes sweeping from John to the pen and back to John again, full of the lazy derision that often came with one of these moods.
"I'm writing a letter and I need a pen. Can you pass me one?" John responded.
Sherlock stared at John blankly for a moment, clearly still processing the request.
"You were just holding the pen." He replied, and John nodded.
"Yes, but now it's on the table and I need you to pass it to me."
"I can't pass it to you. You know I can't pass it to you, or is the fact that I'm nearly transparent and hovering not a big enough clue that I'm still a ghost?"
"I know you're a ghost, but it's a simple task, Sherlock. Pass me the pen."
Annoyed, Sherlock made a show of reaching for the pen, his hand sweeping right through it with a faint shimmer as expected. He gave John a triumphant look, but John merely folded his arms across his chest and looked expectant.
"Try again."
And scowling, Sherlock did so and failed again. But now it was clear what the game was, and he realised John didn't want him to give up until he could pick up the pen. So Sherlock kept trying, even after John got bored of watching and wandered off to do some work on his laptop, only glancing over occasionally to offer some encouragement.
They both jumped in surprise when, a few hours later, the pen rolled right off the coffee table and onto the carpet below after Sherlock flicked it in frustration. John stared at the pen, then looked up at Sherlock with a grin. Sherlock met his eyes with a grin of his own.
From the pen, Sherlock worked his way up to bigger things, slowly increasing his strength and ability. Moving things and maintaining a solid presence or force seemed to require a lot of energy, so it always worked best when Sherlock was frustrated - that manic energy that used to wreak havoc upon the flat now channeled entirely into throwing a pen against a wall.
After a few frustrating months and a number of smashed dishes, Sherlock could manage to lift light objects like sheets of paper with ease, and heavier objects like a small mug with considerable effort. But the first time Sherlock managed to lift something really heavy (an old encyclopedia from the bookshelves) he disappeared for a whole week. John got into quite a state during that time, convinced he really had lost Sherlock forever this time, and blaming himself for overworking Sherlock even after death. When Sherlock finally appeared again, John tried to draw him into a tight hug and passed right through him, cold.
"Apologies, John." Sherlock murmured, looking somber. "I don't think I have the energy for that right now." And John nodded because that made sense, and shivered as he stepped out of Sherlock's ghostly presence.
Though Sherlock acted like nothing had changed, he was a lot more careful when pushing himself after that.
It had been nearly two years since Sherlock's return before he encountered anyone besides John and Mrs. Hudson. He was stood besides the windowsill, playing the violin with John, as they often did now. It was an easy way to feel alive again, as John had become practised enough to match his ability and Sherlock could become corporeal enough to only apply physical pressure to correct John when he made mistakes and guide him into playing properly without getting exhausted. It was an intimate and absorbing task, and neither of them noticed when Mrs. Hudson let Lestrade into the flat, a case file tucked under one arm for John.
It was an old case, and a challenging one at that, but new evidence had recently come to light on the matter, and Lestrade was hoping John could help him with it. He wasn't Sherlock, no, but he'd lived with the man for long enough and worked with him enough to know his methods. And a fresh perspective could never hurt, even if his suggestion only lead to further evidence to confound them rather than the solution to the case. And besides that, Lestrade suspected John might be in a better mindset now, and would be more comfortable in crime-related environment.
Lately he seemed happier than ever, even compared to before Sherlock fell (God rest his soul). Over drinks, John told him about learning to play the violin and how it was good to have something he could pass the time with when he was at home. His eyes were bright in a way Lestrade had never seen before as he talked about it. He had the distinct feeling there was more to the story than John was letting on, but whatever it was, it couldn't be a bad thing if it stopped the man from being depressed after losing Sherlock, and Lestrade wasn't a man to pry. Hell, it probably helped John feel closer to Sherlock.
So Lestrade was not surprised as he headed up the flat accompanied by the sound of the violin in a vaguely familiar melody (probably one of Sherlock's compositions). He was most definitely surprised when he arrived in the living room to find John AND Sherlock playing the violin.
They seemed to occupy the same space, Sherlock's body unnaturally pale and shimmering where it seemed to overlay or melt into John's (who appeared very solid, as usual). John seemed to be doing the majority of the fingerwork, hands dexterously shifting and pressing, moving from one chord to the next as he drew the bow over the strings. And Sherlock's hands seemed to lead the way, floating over the strings and constantly flickering softly as they moved in and out of John's hands like moonlight on a rippling shore. Every now and then, Sherlock's hands would appear briefly solid, pressing John's fingers down upon the strings to correct his tension, or pull the bow more firmly for him, before returning to their usual translucent appearance, like sheer fabric.
The moment looked private, serene. Gorgeous.
...And Sherlock was a ghost.
Lestrade collapsed.
At the sound of a body crumpling to the floor, both John and Sherlock spun around, the music coming to an unnatural, squeaky halt.
"Greg!" John exclaimed, quickly setting the violin and bow aside to check he was alright and bring him round.
"A case!" Sherlock exclaimed, diving for the files that had fallen to the floor instead.
And so life goes on in Baker Street, even after death.