'Sherlock?'
First are the dull thumps of the stairs.
There are 17 steps to be exact, but with the skipping of steps from long legged strides, John can only differentiate 9 thuds.
John's vision is blurred, like an out of focus camera, but he can still make out the image of a tall, thin figure emerging from the doorway. He can distinguish a shock of dark hair and a long, black coat as the figure nears, convincing him of the person's identity.

'Sherlock! Sherlock, it's you. Oh my god, finally, I can't believe…'

"JOHN? Oh god. John, please. Can you hear me?"

'What's that Sherlock? Of course I can hear you! Well, my hearing's a bit fuzzy, but I can still hear you,' John replies with a weak grin.
He feels tired and sluggish.
But.
There's no time for sleep.
No, not yet.
Not while he still has time to see Sherlock.
This was his plan, after all. And it worked.

Of course it worked.
It had to work, right?

John Watson was not a religious man, but it was his final battle cry, his last resort, his definitive ultimatum. He'd gone out on a limb on this one, but hell, look.

It worked.

"Stay with me. Stay with me John. Stay with me." Sherlock's voice is frantic, words tumbling from his lips in a low frenzy. He didn't even need to look for the small black box or the syringe or the clear vial to know what John had done.
Sherlock could just tell.
Breath shallow in ragged and strained gasps, bluing lips, muscles twitching spastically under the skin.

And the eyes.
Oh god the eyes.
Pin-point pupils dialed inwards, exposing the full extent of the doctor's steel blue irises.

Sherlock had seen the same eyes before, years ago, when he'd looked himself in the mirror, shaky arms gripping the countertop and parched tongue licking cracked lips before he collapsed.

"John, oh John, what… what have you done," Sherlock whispered, wrapping an arm around John's back, trying to support the delirious doctor.

'Sherlock, c'mon. No need to get all remorseful on me, cheer up. I haven't seen you in three years! Let's talk! We've got all the time in the world now,' John smiled up to his best friend as he felt himself being propped up from the ground. He didn't understand why the detective was acting so oddly.
Sherlock should be HAPPY to see him.

So why wasn't he?

Cradling the ebbing form of John Watson, Sherlock heard the doctor attempt to mumble out some words.
John's breath was too shallow to form any real language besides a slew of airy slurs that even Sherlock couldn't decipher.

All he could do was hold the doctor. Hold him till he was gone.
And that wouldn't be long.

Sherlock knew the effects of what he had bought all those years ago and stashed in his room.

He knew it would be over soon.

John didn't understand when he felt a tear drop from above. It landed on his cheek and slid down, leaving a trail of moisture.

Then there was another.

And one more.

Again.

'Sherlock! Stop it! Why are you crying? We're together, now. Forever! Or, at least this is how it's supposed to work, right? Come one, mate. Seriously-'

"Sherlock…" John nearly whispered.

The detectives eyes widened and he leaned nervously over his friend, brining a hand to John's head, carding long fingers through the sandy blond hair.

"John. I'm here John."

"Thenn… wh… why th'crying Sshh…"

"Shh. Shh. Don't speak, John. Please. Just-" there were tears flowing freely now, and Sherlock had to bite back the sobs that threatened to take over his speech, "-just rest. Be calm. It will… It will be over soon."

What on earth could Sherlock mean? Over?
Of course not! This was just the beginning! How silly his genius best friend could be at times.

"Now… we're tog'thher. S'how it goes, I thhhink. Forever. Togethhh…"

No.
Why.
Oh god.
John.
Why.

"Y-you… You did this for us?" Sherlock managed through shuddering gasps, clutching his friend tight. "John. I'm sorry. I'm so sorry. I was never… I was never dead. I meant to tell you. I really did. God, why, why, why have I done this. I was wrong. I was so wrong… what have I done." The words were cracking, his voice high and forever teetering on the line of sobbing. His hands were shaking nearly as much as John's as he clutched his fingers into the oatmeal jumper, trying as hard as he could to keep from breaking down.

But he couldn't. Not yet.
He had to make these last moments last. He had to burn them into his memory for the eternity of his life, remember them as if his life depended on it.
So he held back the sobs, the screams, the feeling of letting go, and chained them in for as long as he'd be able to stand, if only to spend his last moments with John. He tried to smile, and it came out as a heart-wrenched curving of his lips, unable to façade into true happiness. He wanted, he really did, nothing more than to give one, last, sincere smile to his best and only friend, but he couldn't bring himself to do it.

He didn't have it in him to lie to himself like that.

But he tried his best.

There was a sudden realisation for John. It felt almost as if he'd been physically hit, but there was no tangible pain. There was first a sudden hypersensitivity of his hearing, honing in on and amplifying the slightest of noises in the flat: Sherlock's pained breathing, the rhythmic pattering of rain on the roof. Then the focusing of his vision, bringing everything into near over-focus, sharpening the lines so dramatically that he could count every one of Sherlock's eyelashes if he wanted to. His eyes tore from the frantic face of his friend, listing down to the ground to observe the objects there: a black folio like case opened and empty, the drained glass vial, the syringe.

And then came the mental clarity.
The acknowledgement.
The reality.

"Ohhh no. No. Oh whattt've I… oh g-" John was cut off by a constricting of his chest, causing his breath to hitch and strain as he struggled to breath.

Sherlock just shook his head, black curls bobbing about, and continued to cry silently, never letting his fierce hug on his friend. The detective didn't trust himself to talk.

He didn't want to say anything he'd regret, because, hell, he'd never get the chance to take them back.

John, now in his hypersensitive state of acute realisation, was very aware that his body was going to give at any moment. He'd never much studied the effects of heroin overdose, but he didn't need to in order to feel his heart slowly giving out and his lungs failing to function. His system was shutting down, and he was slowly beginning to slip into fuzziness once again, being pulled under the surface of consciousness by the heavy drug. He was drowning.

He didn't have long.

He wished he had the time to think of something clever, sweet, or memorable to say to his friend. He wished he could have made an apology- because god damn had he been stupid and had he been wrong!- to let Sherlock know just how much he meant to him.

But he didn't.

So, with his final dying breath, clutched tightly in the arms of his best friend, Sherlock Holmes, he muttered the only thing that could come to mind as his body shuddered and stilled.

"Please, god, let me live."