I do not own the story idea, or any of the characters mentioned. I merely wrote it based on something I saw a while back, and out of pure love and joy for the show. Feedback is greatly appreciated. :)
Sherlock stood to the left of John Watson, his best friend, and watched in hidden sadness as he and Mary stood face-to-face, exchanging their vows. When the priest asked if anyone would like to object, Sherlock had to bite down on his tongue to keep quiet, else he would have done so. But he would never do that to John; not now, not today, not ever.
He did not want to risk his friendship with the man; the man who saved his life day after day; the man who kept him in line whenever he got too far; the man who made sure he slept, and ate, and took care of himself. Sherlock just couldn't risk it.
With their vows now exchanged, and promises of a future gone by, they came to the most important part of any wedding; the 'I do's'. Sherlock lowered his gaze to the ground, placed his hands behind his back, and listened respectfully as the two of them talked and repeated everything the priest told them.
John said his part, then Mary said hers.
John said 'I do', and Sherlock held his breath, waiting.
He looked up and saw Mary grinning up at John, then looked back down.
"And do you, Mary Elizabeth Morstan, take John Hamish Watson, for your lawful wedded husband, to live in the holy estate of matrimony? Will you love, honor, comfort, and cherish him from this day forward, forsaking all others, keeping only unto him for as long as you both shall live?" The priest read from his book, awaiting her response.
Here Sherlock releases the breath he had been holding for so long.
He looked back up once more and watched as Mary said the magic words, and shook as he said them quietly to himself along with her, his own words but a whisper in the wind. He looked back down to the ground one final time, but had he looked at John the moment those two words left his thin lips, he would have seen John's body go tense.
Sherlock just couldn't bring himself to look at them anymore; not because he's not happy for them, oh no. He's immensely happy that John has found his own happiness. He just wishes it were with him, is all. But, beggars can't be choosers, so they say. Sherlock can live with that, if only for a while.
With the rings on their fingers, vows in place, hands locked together, and a kiss to seal the deal, John and Mary made their way to the dance floor to share their first dance together. John glanced over to where Sherlock had been standing next to him, only to notice that the detective was nowhere to be seen. He frowned. Surely Sherlock wouldn't leave his best friend's wedding so early? Then again, he thought to himself, this is Sherlock Holmes.
John danced with Mary throughout four or five songs before he excused himself so he could go look for the man. She asked if he would like any help, but he declined and insisted that she go and have fun.
John wandered about the grounds in search of his friend, but he could not find him. He tried not to be upset about it, but he couldn't help the sudden feeling of sadness flush within him. He had heard Sherlock, most definitely; but he did not know what to make of it. He had not said anything beforehand, nor did he show any sign of attraction; but if he did, then he hid it well.
John resigned from his search and went back to Mary, shaking his head in the negative, signaling that he couldn't find him. Mary just frowned for a moment before pulling him in for another dance to take his mind off of it.
Sherlock, on the other hand, had gone back to Baker Street. He detested weddings. Too many people. Fake people, people you haven't seen in years, people you haven't even heard of nor care about getting to know. Sherlock detested it all.
Once he arrived back home, he made his way upstairs and immediately went for his violin. He picked it up, placed it under his chin, then picked up the bow and began to play.
He played for hours.
He played out his feelings, writing everything down, composing. He spent the entire night doing so, not realizing he had stayed up well into the next day.
Sighing, he put his violin away and went straight to his bedroom, changed out of his suit from the wedding and into his pajamas, then threw himself onto the bed.
A few hours of sleep later, Sherlock got up, took a shower, and continued with his composing. When he was finished writing it all down, he recorded it and later named it John's Lullaby, then folded it up and stuffed it into a white envelope, sealing it tightly.
He wrote down the information needed in order to mail it off, then sent it to John and Mary with a side note at the bottom that read: for the baby.
Sherlock may not understand John's choice of companion, but he did understand the man's happiness, and that is all he cared about. He will do anything to make sure that John stays happy; even if that means he won't have any time for his best friend anymore now that he's got a new one, including a baby on the way.
For John, Sherlock reminded himself, I am doing this for John.
