Author's note:And here it is - the final chapter :) It's really just a short piece to tie up the story.

Thank you everyone who stayed with this series to the very end :)

Enjoy!

Chapter 16: What people forget about the greenhouse effect (or The things they grew back)

The flight back to London smells like aeroplane plastic and generic air freshener, tastes like stale tea, and leaves the oily film of travel on skin. It's too long. It's bumpy, the air full of road-holes. But there's Sherlock, in his seat, next to John, very much alive. And there's John, right next to Sherlock, very much not gone.

The flight smells like plastic, tastes like stale tea, and leaves them grimy. Ask John and Sherlock what they think of it, and they'll tell you it's glorious. Looking at them, you wouldn't know what they've just been through. You wouldn't see the lightest of twitches each makes towards the other when they drift just a bit too far away from each other, an invisible tether tensing up and pulling them back, closer, closer. You wouldn't know that they've just walked back from the edge – literal, metaphorical, or whatever other kind you wish – because that's how it works. You look at people and don't really see a thing. You never know what's going on inside them, whether it's just an ordinary day for them, or if right at that moment, just as you are looking at them, unconnected, irrelevant, there is a tectonic shift taking place, some major event breaking them apart or sewing them back up underneath that frail sheath of skin and kept-up appearance. So, you wouldn't know, looking at Sherlock and John, of the yearning and the urgency that bites their skin like a puppy not yet aware of its own strength. You would pass oblivious past the intense feeling of being very, very lucky that makes every mundane little thing – the pattern on the seat upholstery, the random flight attendants nice-yet-slightly-crooked smile as she passes them their food, the blistering of clouds as the Sun sets past them – a spectacle.

When they land, Sherlock and John are greeted by an unexpected, yet not necessarily unwelcome, greeting party. The feelings both men hold towards the figure standing seemingly casually (though that is almost never really the case) are far from simple or straight-forward, but in any case, the both know there is a link there which cannot be denied.

Mycroft is leaning on his umbrella, suit-clad despite the warm, humid air that's brimming with the static of an oncoming storm. Upon seeing his brother and his blogger descend the stairs off the plane, there is a subtle shift in Mycroft's features that almost looks like a tic. Almost, but not quite. There are markers, Sherlock knows, which can be used to read emotion off human faces like script off parchment, but even if there weren't, even if there was just the sheer feeling of it all, Sherlock would guess this one right. Because, really, it doesn't take a genius to deduce the relief on Mycroft's face. Because, really, it doesn't take a genius to deduce the relief on Mycroft's face.

Ages from now, in a world which will no longer contain Mycroft Holmes, an older Sherlock will think of his brother and, if this older Sherlock proves to be a fraction less proud (pig-headed, John would say) than the present one, he may admit to missing his brother. Probably, not, though.

(But he will. Miss him, that is.)

Ages from then, in a world which will no longer contain either of the Holmes brothers, no one will know the depths of loyalty and betrayal, trust lost and long not retrieved, (but trust somehow re-built in spite of everything) that once ran between two siblings. But maybe – just maybe – two brothers will run through that over-grown garden with the empty houses for bees and glass castles for flowers, two boys laughing freely over a shared amusement the way only brothers can. They won't know their laugher will echo that of another pair of boys. They won't yet know the dangers of petty feuds and childhood resentments cultivated to adulthood. They won't be aware of what a precious thing a brother is, both fragile and indestructible, at times. It will never have crossed their minds that there may come a day when they will drift apart, find themselves on opposite sides of a fence, so to speak. Because they will be brothers, at that age when a brother is as sure a thing as sunrise.

But that's ages from now – a now that's marked by Sherlock and John facing Mycroft's solitary figure on a taxi way lit by colourful signal-lights. For an awkward moment, Mycroft's throat works as if there's chalk powder lining it, insulation to prevent speech from seeping out. But it's Mycroft, so words find their way in the end.

"Glad to see you both safely retrieved."

"Yes." Sherlock replies, voice even and unreadable, because there is another voice running an inner monologue, battling between 'Mycroft sent John into danger' and 'yes, but Mycroft did so to save me'. There is the ever-unresolved issue of brotherhood, their prickly cactus of a connection, and for one, Sherlock is content to let it rest for tonight. Because Mycroft is Mycroft, and Sherlock is Sherlock, which only means the complications will be here tomorrow. For now, it is enough that they are both quite aware of being happy (well, happy doesn't really relay the complexity of the feeling) to see each other, an equally aware of the fact that neither would admit it out loud.

"Well. It's good to be back." John cuts in, catching the vibrations of all things unsaid (honestly, sometimes he wonders if Sherlock and Mycroft are quite aware that they almost reach telepathy from time to time). "But if you don't mind, I myself am quite knackered."

"Yes, of course" comes Mycroft's reply, his voice cool and collected if a bit distant. "Please, the car is waiting. I am sure you are in somewhat of a hurry to finally get back to Baker Street."

"Couldn't be more right." John says, sliding into the black vehicle, leaving Sherlock and Mycroft standing in the pre-storm air. Before Sherlock can speak, Mycroft reaches into his pocket and draws out a simple box. He offers Sherlock a cigarette. Sherlock takes it, and for a second the flicker of a lighter flam illuminates his face from below.

"You counted on this didn't you?" Sherlock's eyes aren't on Mycroft but roaming along the airport, as if awaiting a passenger. He blows smoke out through his mouth. "You counted on John being stubborn enough to push against your advice and going after me."

"I counted on John putting your well-being above all else. Nothing more. And nothing less. I am not half as Machiavellian a mind as you seem to think, brother", Mycroft replies, playing with the cigarette box.

"No, you're probably tenfold the Machiavellian mind I think you, Mycroft", Sherlock retorts, bringing his gaze around to stare at his brother.

"I didn't manipulate John into going after you. In fact, I was very adamant about him remaining here."

"Were you, now?"

"I believe John can verify this fact." Mycroft's face is a blank cast waiting to be painted with shades of feeling.

"If you were so adamant, you could have stopped him from going."

"I asked of him to choose. It would have quite defied the purpose of the exercise if I had met his choice by denying it."

"In other words, you were never really counting on him to choose to stay."

"No, Sherlock. I was never really counting on him not to choose you."

This seems to come to Sherlock as a surprise – or better say, as a fact so obvious that he can help but wonder how he was not seeing it all this time.

"You sent him into danger", he says, trying to stare Mycroft into obedience.

"I sent him to rescue you." Mycroft replies, unruffled, "Besides, he would have gone either way. At least this way I could do something to help keep him safe. Keep both of you safe."

By the time Mycroft finishes speaking, the glowing red-orange dot of Sherlock's cigarette reaches the butt of the stick, burning a little too close to comfort. Sherlock drops it on the tarmac, along with his gaze, and stomps out the last of the fire. He moves to open the car door (which John has tactically closed behind himself), only to stop with his hand on the handle.

The sky is darkly illuminated in all shades of burdened as Sherlock looks back to his brother.

"Mycroft...thank you."

A nod, a scratch of the umbrella tip along the coarse asphalt and then the car doors are slamming shut, tires screeching away, burning trails into the road.

The night smells like burnt rubber and cremated tobacco. Like gratitude and relief, and all the unsaid sentiment in-between.

An hour and several traffic jams later, John and Sherlock climb the stairs to 221B. The building sighs and moans, the foundations settling as balance of tenancy is restored. Quick ascent up the stairs and then there is the longed-for click of the door opening and then closing. The world is left on the other side of the partition.

"God, I can't believe it's only been a couple of days since we left here", John says, allowing his lungs to fill with that well-loved, eloquent dust of 221B.

The door of the flat closes, softly-but-surely, and marks the tipping point.

"John." Sherlock calls from behind John's back, leaning against the closed door.

John turns to face his flatmate, and just like that, the excess of air dividing them finally becomes unbearable, and Sherlock moves to John (or John to Sherlock, there's no definite verdict on who moved first), obliterating the hated distance. Before anything else can get in their way, hands latch onto bodies, and a tug-of-war sort of ordeal starts to unravel as caresses give way to pulling, closer, closer.

Fabric whispers, betraying secrets of lovers to the walls that know them oh-so-well. It is different, this time, this third time. Different from the intense high of the first time (fires) and the frenzied search for band-aid oblivion and deceit of the second (floods) – the third time is something new, young and bright, but endlessly more mature, like a sapling growing from the burnt remains of an ancient oak, youth saturated with the wisdom of ancestry which roams its veins.

You'd call it love, but you'd be doing it injustice. Because it isn't just love, glorious as it may be. It's devotion and understanding, acceptance and a vow. More than anything, it's creation in face of all the destruction.

(You'd call it love and you'd be right, because isn't love – real love – just that? All of that? Complicated and difficult and hard work? Isn't it glorious? You'd call it love. You'd be right.)

Fingers dance and it's an intimate choreography to a tacit composition. Sherlock's fingers work on the buttons of John's shirt and John's hands deal with Sherlock's cuffs, skimming around each other like trained birds flying in formation.

Fingers write and it's a pen-pal correspondence on skin, licks of tongue for the postmarks to stick. Scrapes of fingernails grate like talons of messenger-pigeons taking off and landing on concrete. Breaths are flaps of wings that carry words of yes and always and better this time around. They're still standing on their feet, grappling at cloth (that's slowly vanishing) and skin (that's rapidly being uncovered).

And then everything stops. For a moment – just a moment, that's all they can spare, all that lust and need allow, but a single moment is better than none – John and Sherlock just stand there, John's hands splayed over Sherlock's bare chest, skin-on-skin ignition points lighting up the world. Sherlock's fingers still, stopping mid-movement on the band of John's trousers, caught in fabric like fishing hooks in the deep blue, fishing for a miracle. (Catching one, too.) Eyes lock over the little distance they can stand to tolerate, hot, humid breaths coming out in puffs, like memories of the greenhouse and the warm air that surrounded them there. The world stands immobilised just long enough for the full realisation of all that could have been lost to come down crashing. But more than that, it allows the amazing against-all-odds nature of the current moment to rip through the surreal fabric of the last few days. Or years. A lifetime, it would seem.

"John..." Sherlock's voice is soft, like black, rich soil; like tender hands sowing seeds. He leans his forehead against John's, and for some reason it feels as intimate as sex, at that moment. It's a plea and an exultation, a shout across rooftops saying "we made it!".

"Oh, god..." John's voice is pain and joy and little impossible things that refuse to be named, little children of cosmic plans and pure coincidence. It's the voice of a man just saved from the gallows. His hands move over Sherlock's chest, to roam frenziedly over his abdomen and back, up to the nape of his neck to pull Sherlock's mouth to John's, and just like that, the moment is over and the world tilts back into motion, just in time to witness this utter surrender.

Because that's what it is – surrender. Even the victors have to give in to a force more powerful than them; to faith, or love, or whatever else you choose to believe in. They must surrender and know that, despite the temporary triumph, victory is fleeting. All they can do is choose to await the next pitfall either alone or with someone by their side.

For Sherlock and John, it was never really a question. Also, for Sherlock and John, doing what one must was never quite a clear concept. So, they refuse to surrender to anything. That is, they refuse to surrender to anything but one entity, and one entity alone - each other.

Breaking the kiss, John takes Sherlock's hand, and together they make it to Sherlock's (their) bedroom, their steps deliberate, their skin buzzing. Sherlock could swear the feeling in his chest is a pneumothorax, because that's definitely what it feels like (though John wouldn't tell him it isn't, because John would recognise a pneumothorax) – too big for his ribcage, too vast for his being, this endless yearning. It feels like dying, a little bit. It feels like being truly alive in that way that comes along so rarely.

It's precisely how love should feel.

Sherlock's body's bare, save his pants, as is John's, as they fold together onto the bed, side by side, legs tangling in a wish to press their bodies as close together as possible. When John's hand wanders between Sherlock's legs to palm over the heat there, Sherlock's lungs push air out so violently that Sherlock's vocal chords are caught by surprise into producing a moan.

"John!"

Sherlock plunges his free hand (the one not currently in the service of teasing the band of John's boxers) into his hair, pale fingers tangling black curls around them like flax on spindles, and his whole body arches towards John the way plants lean into sunlight. But John stops (damn him) and takes Sherlock's hand out of the black mess of curls. And because this is John – and John is always a surprise – Sherlock isn't surprised to find himself surprised (they're a paradox. It's not simple. But then again, they were never made for simple.) as John takes to kissing each of Sherlock's fingertips.

The gesture is so reverent that Sherlock wonders how it is possible for someone to feel even more naked than being stripped bare. But he does – oh how he does – because this is more than nudity. This is being wanted and cherished. This is acknowledging the stupidity of ever allowing oneself to love – to entrust another frail, mortal being with one's happiness, even if only with a fraction of it. Acknowledging it – and embracing it.

By the time John's done with kissing his fingertips, Sherlock's managed to tangle their legs so that when he rolls onto his back, he pulls John with him, successfully splaying him on top of Sherlock. Both men groan at the contact, as each shift and slide threatens to bring things to an end (and what a sweet threat that is).

Finally, the last of clothes are shed and as Sherlock and John start moving together, the silence is broken by the sound of rain starting to wash away the grime of the week. It rains hard, infinite little heartbeats pounding on glass and concrete and roof-tile, hard, hard, like fingers prying to catch at skin, and somewhere in London, there must be a fire burning, a flicker licking at air from a tip of a candlewick, a lighter hissing ignited gas at the round edge of a fag, and even if there isn't it doesn't really matter, because Sherlock could swear that all the fire and all the water and all of the world as such is really just a bad carbon copy of this, this world John and he are busy creating, this glorious ecosystem founded on devastations of the past.

The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface and the lower atmosphere, it results in an elevation of the average surface temperature above what it would be in the absence of the gases. When enhanced through human activity, it is the main cause of global warming, a steady and constant rise in Earth's overall average temperature.

This increase in temperature is predicted to have adverse consequences on Earth's climate, leading to increasingly higher temperatures which may cause fires during summer, and melting of the ice caps, which will result in, among other things, an increase in the number of floods.

What people often forget is that the greenhouse effect is a natural phenomenon. Without it, the Earth would be a hostile, frigid place, its average temperature a harsh -18 degrees Celsius. It is only when people temper with it – pollute it, clog up the atmosphere, act recklessly – that it becomes a problem. But handle it with care, and the greenhouse effect makes Earth habitable. It's what makes Earth home, allows life on it to thrive.

As dawn breaches the thin diaphragm of the horizon, John looks at Sherlock, amidst of scattered remnants of two lost worlds – the ashes, left over by the fire, and the mud, left over by the flood, make for a fertile soil – a basis for new life, constituted out of leftover traces of destruction. Fires and floods, a necessary antithesis allowing for new creations.

John looks at Sherlock the way he will look at him for many years more, and sees possibility (inevitability). John looks at Sherlock with the ages that are yet to come, ages from now when they will begin again and again with each sunrise and each nightfall, lurking somewhere in the whirls of fingerprints, in the shadows between lashes.

He doesn't see the cottage and the overgrown garden and the path stones that they will lay down together. He doesn't see their initials rooted to the earth long after they themselves have been put to sleep in it. He doesn't see any of this yet, because these are early days and this John would find the idea of that life a horrifyingly boring prospect. But he will see it, eventually. He will.

Because right now there's the promise of starting again, hard-won understanding of misguided gestures, fire-forged patience, and water-washed willingness to do better this time around. These are the things that allow life to thrive.

These are the things they grew back from ashes and mud.

It's a new world, one that will be harder to destroy. Not because it is indestructible, nor because there won't be challenges – oh, there will be (John wouldn't have it any other way) – but because this time John knows, as does Sherlock, that, if handled with care, they allow each other to thrive.

They aren't each other's doom. They are each other's greenhouse effect.

FIN