Note: This is my first time actually writing fanfiction, so I'm a bit nervous. And of course I decided to write it from Sherlock's point of view (more or less), which is one of the hardest things to get right.
Also, this hasn't been beta'd, any mistakes are my own.

Sherlock turned his new mobile phone over and over in his hand.

(Smooth. Owned for less than a week. No scratches. One dent on upper right corner. Fallen out of pocket onto wooden floor.)

Pointless. No need to deduce his own phone.

The motion of turning it in his hand was comforting. Neuro-musculature producing emotional sensation. Filed under nervous habits for future investigation.

The dull roar of the plane buzzed in the background, numbing his ears. He'd been sitting in the same seat for two hours, and the boredom was creeping up his legs and wriggling across his skin.

He wished he had his violin.

The man in the seat next to him was snoring gently, a thin trail of saliva leaking from his mouth. Sherlock eyed him disinterestedly. He'd already deduced that the man was an unemployed insurance salesman on his way to his brother-in-law's funeral, even though he'd never liked him, because he wanted to reconnect with his estranged sister in hopes of getting a job. He had two large dogs and lived on his own but was still in love with his last girlfriend.

Utterly dull.

He had considered talking to the man, but quickly rejected the idea. It would probably start a fight, which might be diverting, but wouldn't be interesting without John there to fix it.

"Alone is what I have, alone protects me."

Alone, lone, lonely, lonesome.

"No. Friends protect people."

Music was spinning in his head. Emotional response. Sound could cause emotion in others without their knowing the cause. If he had his violin he could create the notes turning in his mind.

Sherlock looked down at the phone in his hands and unlocked it.

He'd set the password as 1895. The number on which the counter on John's blog had been stuck that he once thought was the password to Irene's camera phone. Really, it had only been that the counter on John's blog was faulty.

Foolish gesture.

Sentiment.

This is your heart, he had once said, and you should never let it rule your head.

He couldn't even follow his own advice.

"Caring is not an advantage, Sherlock."

Sherlock tapped on the address book in his phone and opened it. John's number was staring back at him.

The music in his head sounded like tea and jumpers and hands that did not shake when they pulled a trigger and killed a man.

"I'm a doctor, let me come through." Panic tore the edges of his voice. "Let me come through please. He's my friend." His voice broke. "He's my friend, please."

(It wasn't John's reaction that surprised him, it was how much it had hurt.)

Analyze data.

Friend:

noun
1. a person attached to another by feelings of affection or personal regard.
2. a person who gives assistance; patron; supporter.
3. a person who is on good terms with another; a person who is not hostile.
4. a member of the same nation, party, etc.

Synonyms: mate, buddy, companion, acquaintance, associate, ally, confidant, intimate, comrade.

Soul mate.

(John.)

The words were not helping, and Sherlock hated it. They clung heavy, labels on something that defied identification. There were no words, what happened when there were no words?

John.

John.

It was indescribable. He was thoughts and emotions and could not be articulated. Words melt and break before the mind.

Break, broke, broken. Splintered, shattered, smashed, crushed, damaged, injured, cracked.

"No, Sherlock, don't—"

What was it like to be broken?

Not whole.

He had told him. Why didn't he listen? It's a trick, it's all a magic trick. John was clever (for an ordinary person). Surely he could figure it out.

If he tried to play his violin on the plane they would probably make him stop.

There was a ding and the seat belt signs turned on. One of the cabin crew announced that they were experiencing some turbulence. Sherlock listened idly. She had quit smoking three months ago, but she still longed for a cigarette, and she would probably sneak one when they landed. She was dealing with stress at home—death of a loved relative, he was fairly sure, most likely an aunt or uncle.

John's fingers were on his wrist, checking for a pulse, desperate for a sign of life.

There was none. Sherlock had made sure of that.

The woman finished talking and walked down the aisle, her heels tap-tapping on the gray carpet. Sherlock watched disinterestedly as she passed his seat. Definitely an aunt that died.

John still hadn't realized it on the day that he and Mrs. Hudson visited Sherlock's grave. Even from a distance, Sherlock could tell that he hadn't been eating or sleeping well. He had been missing work as well, and he hadn't been back to 221b since the day of the fall.

Grief.

(Was it similar to what he was feeling now?)

It had been a mistake to go to the graveyard. To see John hurt too much.

He had wanted to see him once more before he left, reassure himself that he was all right.

John had cried over his grave.

Why.

(Words, words, where were the words?)

He was not worth it. Sherlock was not worth those tears. Surely John must know that. Grief for a fake death and tears from a good man.

John's melody turned incessantly in his head.

If it had been reversed, if it was he who thought John was dead, Sherlock was sure he would not be able to continue. He lived knowing John lived.

And he had stood there, hidden in the trees, and watched John square his shoulders and walk away, straight-backed and strong.

Sentiment.

Sherlock had always prided himself on his lack of it.

Affection, caring, emotion, sentimentality, attachment, compassion.

(LOVE)

Sherlock realized that he had been tapping his foot on the floor and made himself stop.

The flight was far too long. Too much time to think.

The insurance salesman next to him murmured in his sleep. Sherlock was 92% certain that he was dreaming about his ex-girlfriend. Then he immediately deleted the useless information.

He wondered what John was doing at that moment.

He hadn't properly considered the effect it would have on him, he realized. He had thought of it, but it seemed inconsequential at the time. John couldn't know. He would be in too much danger if he did, with Moriarty's operatives undoubtedly still trailing him. Once Sherlock had eliminated them, then he could return.

He hadn't thought about the in-between time. He just assumed that John would be all right.

Now he wasn't so sure.

Surely John would understand. There had been no other way.

The insurance salesman's head slipped down from his headrest and he woke with a start. After the initial shock, he blinked and looked around blearily, and then gave a massive yawn and shifted in his seat. The trail of drool still glistened on his chin. It was irritating to look at.

John might never forgive him.

Sherlock turned away irritably and stared out the window. (Cumulonimbus clouds piled high meant that it was probably raining on the ground.)

Forgive, pardon, excuse, release, condone.

Overlook, disregard, ignore.

(The tray tables had not been cleaned for the last three flights.)

Even if he spent his whole life making up for it (how ridiculously unbearably tedious), it would be worth it if John was safe.

Sherlock tried to picture John in the seat next to him. Brown shoes, jeans, jumper, black jacket. Asleep, head resting gently against his own shoulder, the sad lines gone from his face. Content.

(How was it that in a world full of boring, ordinary people, someone like John existed?)

It physically hurt to blink and see the insurance salesman next to him, now cleaning his glasses with a handkerchief.

(Why did it hurt?)

Words were failing him and Sherlock felt like he was drowning. Ridiculous. One cannot drown without a liquid. One does not drown sitting in a plane in mid-flight.

Not drowning. Suffocating.

Sherlock took a deep breath, feeling the air move in and out of his lungs, proving to himself that... what? That he could breathe without John by his side?

That he could breathe knowing John was alone. Again.

His fault.

Sherlock turned back to his phone and opened a new text message.

I'm not dead

Delete.

You're not stupid. Why can't you figure it out?
You know I couldn't tell you. You are terrible at keeping secrets.

Delete.

I wish you were here

Delete.

I miss you and it hurts.

Delete.

I think I might be broken

Delete.

Forgive me

Delete.

Sherlock huddled down into his seat and pulled his coat around himself more tightly.

By the time they landed, John's melody was a finished piece of music, composed for the violin, that was sad and strong and spoke of home. Sherlock would never have admitted it to anyone, but later, in his unfamiliar hotel room, he played it late into the night, until he was standing back in their own flat and John's name was burned into the walls and there were no words left for anything anymore.