I was listening to Mumford and Son's Timshel while driving to work this morning and this dropped into my head.

Warnings for character deaths.

Characters aren't mine.

Cold is the Water.

The water is surprisingly clean as it pours into the little room. It's not drinkable, it's too salty for that, but it's clear.

For a moment, before it had rushes into his shoes, Sherlock had feels a moment of joy. The water is about two inches deep and yet his socks and feet are dry. He loves the victorious feeling as his man-made shoes thwart the elements.

The water level continues to rise and the water rushes over the tops of his shoes and fills them from the heel right down to the toes. He shuffles them a moment to make sure that the water is evenly distributed.

The water is cold. It very quickly starts to numb his toes.

John's wearing boots today, solid walking-boots. His feet are probably still dry. He is crouched down, his fingers working quickly, checking each one of the links in the thick iron chain, hoping to find a weakness.

He looks up at Sherlock.

"It's solid."

"Yes."

Sherlock hadn't bothered to try. He'd known it would be futile.

"I'd like to try the bolts," John says.

"Fine."

"Do you have anything at all on you? A pen-knife? Anything?"

"No. He's taken everything."

John nods and goes back to the manacles. He tries working at the bolts with his bare fingers.

Sherlock knows that this too will be futile.

The water is rising. It's half a foot deep now. The chains, the manacles, John's hands; they're all submerged.

Sherlock glances down at the pipe they're chained to. Chained around to be accurate.

It's solid too, running from the floor to the ceiling, about an inch from the wall. He's assessed this and there is no way that either of them could break, bend or move the pipe.

John tugs at the chain and the iron of the anklet pulls roughly against Sherlock's skin.

"Sorry," John mumbles.

Sherlock grunts in response.

The anklet doesn't quite fit. It's loose in places (though not loose enough) and tight in others.

If he were able to walk anywhere, it would probably chafe his skin.

If.

John sighs and straightens up.

"It's no good. I can't budge it."

Sherlock doesn't answer. Of course he couldn't budge it. He'd never have been able to budge it, but John, being John, needs to check. He needs to try. Sherlock doesn't judge him for it.

John's right hand is white with cold. He shakes it and clenches it to get the circulation going again.

Another act that is, in the long term, quite pointless.

John leans against the wall. He shivers slightly. Sherlock knows that John's feet must be wet now.

Sherlock leans against the wall too.

The water is cold.

The water is clean. It's almost up to their knees now, but they can still see through it to the seams in the floor. Two massive, iron slabs bolted together.

Everything in this room has been designed to keep the water out. The trouble is, the exact same forces are now keeping the water in.

Jim had been clever. Clever, little Jim.

He'd pierced a hole in the hull, close to the top of the wall. It had taken him a while, but he'd been patient, laughing as he listened to John negotiate and plead with him.

There was a second where John had thought he was getting through. Sherlock had known it was all an act. When Moriarty had completed his work, a fairly small hole punched through the wall of the ship, he'd simply said goodbye and left. He'd closed the iron door and turned the deadbolt.

Sherlock had been relieved. He prefers it when it's just him and John.

There is nothing in the room that can help them. The water gushes through the hull, making a pleasing splashing sound.

It has reached their knees.

The water is cold, crisp and clear.

"If I amputate my foot, we could get free," John suddenly says.

Sherlock looks at him.

"How do you propose we amputate your foot?"

"I could bite through it."

"No you couldn't. You'd pass out before you got very far."

"You could bite through it."

"No, I couldn't. There are several reasons why I won't bite through your ankle. One, the human ankle, while it is healthy, is strong and tough. I'd break the skin, perhaps tear the muscle but I'd never get through the bone. Two, you'd bleed to death before I got very far."

"Even if I was dead, you'd be able to get free."

"Ah, so your last act on Earth would be one of selfless bravery." He sighs and looks at the water pouring in. "Typical."

John sighs too and looks away. "It's too late now anyway. The water's too high. You'd drown before you managed it."

"So I'd drown and you'd bleed to death. I think we can safely say that that plan is quite flawed."

"Well, what's your plan then?"

"Wait here until someone finds us."

"Yes, I can imagine that lots of people would think to look in a small room in the hull of a disused warship."

"It's not a good plan, but it's a slightly better plan than any other."

The water is at their thighs now.

"Right. Good." John says.

They stand in silence for a while. John can't take his eyes of the hole in the hull. Sherlock shuffles slightly closer to the pipe.

The water rises.

The water reaches their chests. Sherlock's chest that is; it's nearly at John's shoulders.

Sherlock knows that his last act on this Earth might well be to watch John Watson die.

The water is cold. Sherlock knows that he's holding John's hand but he's too numb to feel it. He wonders if John felt that sudden, nervous squeeze. If he did, he didn't respond.

John feels fear.

Sherlock finds fear intriguing, as it's not an emotion he often feels himself.

He is reasonably emotional. He can list several emotions that he feels regularly: joy, satisfaction, hurt, anger, lots of anger, even more frustration.

Love.

That one surprises everyone.

He doesn't feel much fear though. He thinks it might be because his brain works too quickly for fear to catch up with it. People seem to need a slow dawning of possibility to feel fear. He's usually assessed all possibilities, selected one, and is acting on it before his emotions or his hormones or whatever have caught up. Fear can't catch him.

John says he's impulsive. He probably is. He doesn't feel the fear that's needed to restrain him.

John feels fear.

Sherlock finds the strength of John's courage fascinating. Sherlock doesn't feel fear, he just acts. John feels fear and acts anyway.

Sherlock's fairly certain that if he was bogged down by all of that fear, he'd never do anything. He'd sit in the flat, wrapped in a duvet, willing the rest of the world to just go away.

John doesn't do that.

John is brave.

The water is at John's neck.

It rises towards his chin.

John sobs suddenly. His face instantly fights it, trying to regain control. He takes a couple of deep breaths.

Sherlock cannot squeeze his hand now.

The water is cold.

Sherlock is numb.

He wonders if he should say something to John. Some words of strength or of comfort, or even of just plain gratitude.

He can't think of what to say.

John looks at him. Sherlock looks straight into his eyes and knows he doesn't need to say anything.

John is standing on tip-toes now. His head is tilted back so that his nose is barely above the surface of the water.

Sherlock frowns at him. He wonders why anybody would want to prolong this.

He supposes it is hope. Perhaps in this last half minute, someone will open the door.

Sherlock knows he must perform his last act. He turns and meets John's eyes. The water is over his mouth but he doesn't tilt his head or look away.

He feels the manacle tightening and pulling against his ankle for a while. It takes longer than Sherlock expected. John fights.

The water is up to Sherlock's nose and he finds that he tilts his head back too, keeping it above the water.

John is dead now. He's sure of it. His body is still as it floats next to him. A tiny part of his hair isn't wet yet.

Sherlock knows that there's no such thing as a soul, but he finds himself desperately hoping, desperately praying, that John's soul has left and is somewhere safe now. He imagines it flittering about the world, ready to settle in some animal or tree, or new-born child. He wonders if he'll ever find it again.

The cold has made him stupid. He screws his eyes tightly closed and accepts that there is no John now.

You cannot drown yourself. You will fight to live. Sherlock knows this to be true.

You can, however, put yourself in a position where you will, with absolute certainty, drown.

He forces his face into the water.

The water is cold.

He cannot take a breath. He can't make his body do it.

He hooks pushes himself beneath John and waits.

There is a sudden change, a sudden banging through the water. He knows that they have come for him.

He hopes he is not too late.

He waits, forcing himself to stay there until he cannot resist taking a breath.

The water is cold in his chest.

He fights it too, but is caught, safely, by John.

He hopes he is not too late.