Author's note: *rises from the dead* Hello everyone! I'm back (beat Sherlock to it! HA!), and I brought with me my first series, called The Greenhouse Effect Series :)

This is the first part, which contains my usual stuff - angst, with a side of angst and ofc Johnlock.

I can't promise everyday updates, but I'll try not to keep you waiting long between chapters, promise :)

Disclamer, as usual - disclaimed!

Enjoy! :)

Chapter 1: Different shades of bright

"Man is the only creature that dares to light a fire and live with it."

- Henry Jackson Vandyke, Jr.

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.

10th January, 2016

Sherlock thinks he hears the pipes moan, and it sounds like ghosts and ghouls and creatures of myth Sherlock never believed in. It sounds as if there's a pigeon stuck in the scratch-scarred wall – like a living thing hopelessly trapped between inanimate layers of plaster, wood, and bricks, trashing in its confinement.

The sound is unsettling, eliciting a surge of anguish as Sherlock presses his palms to the sides of his head, covering his ears and trying to drown it out.

A pigeon in a wall. Moaning pipes. Ghouls and ghosts, indeed, Sherlock thinks, as he listens to the beating of his heart.

One day the world will end. The end will start with fire.

Five weeks earlier (3rd December, 2015)

"Mycroft will spread the word of my supposed relapse...Usually he would try and intimidate every dealer in London into not selling me anything, but this time there is a new spin with which we are going. Apparently this time I have fallen so low that I am beyond salvation, so the only thing my meddling older brother can do, is make sure I get the best produce. He will select the suppliers, thus contributing to my cover. It must seem and feel as authentic as possible, which is precisely why we can't be seen together, or better yet, not meet at all unless there is an explicit need to do so."

Sherlock's laptop lays open on his desk, the keyboard littered with loose paper and scribble-covered post-its. The article on the screen is accompanied by a picture of a body, splayed on the dirty pavement of what appears to be a dingy back-alley, and the title reads "Bad drugs cause several deaths in London". John lifts his eyes from the screen to look at his flatmate.

"Ok." There is something hard in his eyes, but he does his best to keep his tone neutral. Of course, his attempts prove futile, as it is Sherlock Holmes he is speaking to. Sherlock takes note of the straining-to-sound-normal tone and casts a quick glance at John, taking in the subtle shift in posture and tensing of muscles. With an eye-roll and a sigh that would put martyrs to shame, he amends his earlier speech.

"I will acquire a burn-phone, so there is no worry of losing contact, really. I will need you here, as source of information, so there's no reason why we couldn't communicate on a regular basis, say one text per day, which, I am sure, would appease any turmoil this arrangement may cause you to experience."

Sherlock finishes his soliloquy in such a way that John can very clearly hear the unsaid "happy now?" part of it, and the silent question is answered by John with a short nod. Memories of the scene on the roof of St. Bart's, and all the years that followed, are still fresh in John's mind, despite the fact that almost a year has gone by since Sherlock came back. They don't bring it up much, not because neither of them dares but because they've put it to rest, mostly. They've gone through all the motions – the initial tension, the lashing-out, the angry relief, the cooling-down, the heart-to-heart (the male English version of it, at least), and finally, the letting-go and starting anew. John remembers the first few weeks after Sherlock's return and the way the man seemed to wreak havoc on John's new life. If he had not been furious about it at the time, he would have found Sherlock's blatant inability to understand that John's life had moved on – that John had moved on – endearingly typical. The way Sherlock waltzed back into John's life, radiating self-confidence and firm belief that the world stood still during his absence, was what really made John cross at the time. He'd forgiven him, of course, but it took a while for both of them to acclimate to the new order of things. Sherlock, in his tornado-like fashion, blew in and rearranged everything, made space for himself, if somewhat forcefully, in John's new life, which had since become filled with new things and new people, and, logically, this meant that in something had to give. In John's case, the thing that gave was Mary.

Sweet, kind, extraordinary Mary. John thinks that he most certainly could have ended up loving her. At the time, when the world got ransacked by much-wished resurrections, they were just beginning, Mary and he. It wasn't love, not yet, but only soft tendrils of potential and soft prickles of true happiness, re-emerging after a long hibernation. She was never a substitute – no one could ever be that – but she was something light and good, a promise of a new start, appeasement of ghosts and a partner with whom new memories could have been created. She was like candlelight, whereas Sherlock had always been more like an explosion, and where he was spectacular in his flamboyance and force, she had a quiet, soft strength of long-burning light and gentle warmth. For a moment, John indulged in the idea that he could have them both. It even seemed possible, for a while. Sherlock, still learning the new way of things, treated Mary in a way John had never seen him treat anyone – with reserved respect and somewhat awkward consideration. Mary seemed to sense the effort put into it by the newly-revived detective, and rose up to meet every clumsy peace-proffering of Sherlock's. John sometimes found himself standing, jaw slack with something akin to awe, and observing this rare, previously considered impossible event, as if a supernova was being tamed by a flicker of fire at end of a candlewick. But in the end, it made for just a little bit too much fire in John's life. John expected the usual "don't make me compete with Sherlock" argument, but it never came. Mary never accused him of making her compete, nor did she ever ask John to choose. John never gave her reason to – she had never been a substitute, so she couldn't have felt threatened by Sherlock. In the end, it wasn't John's choice at all, but Mary's, and in the end the choice never included Sherlock, not in a way that would render the detective responsible for whatever was to become of John and Mary's relationship.

"One day, you will break my heart, by no fault of yours, by getting yourself killed or injured, and I can do something about it now, before we're in too deep." she said, "I don't want you to have to chose between me and your life with Sherlock, but that means I have to chose between myself and you". And because it wasn't love then, not yet, she chose herself. It wasn't selfish – it was smart. John thinks he might have ended up loving her, ended up wanting to keep her more than he had when they parted, and wonders how selfish that would have been of him.

Still, in those bitter nights when Sherlock is being extra impossible, John sometimes imagines what his life would have been like if he never came back, if it were Mary instead of Sherlock. He never wishes for it, no, never that. He spent too much time wishing Sherlock alive to ever be so stupid to wish anything else, but he can't help comparing the pre-Sherlock and post-Sherlock look of his life – the order and the chaos, the steady-paced routine of the former and the fast-paces irregularity of the latter. Sometimes, when Sherlock loses his temper or says something exceptionally callous, John almost blames him for Mary...but not really, not ever, because he knows Sherlock didn't really have a say in it. One cannot blame a tornado for tearing apart houses – it's what tornados do – but they can blame themselves for not building stronger a house. Or they can choose not to cast blame at all, and build a new house.

Either way, when John's steady happiness with Mary was put to rest, despite Sherlock's blinding brightness, John could still feel the world grow just a bit darker as the soft candlelight got extinguished. And then it was just John and Sherlock, once again. Things never went back to precisely how they were three years ago – they couldn't have – but for the last six months or so they've been having a pretty good run.

Sherlock seems to be slowly learning few things about humility, and John feels his tolerance of Sherlock's less favourable features (tolerance which suffered a great regression from its original form, in the first few weeks after Sherlock's return) grow steadier and stronger with each passing day. So, when Sherlock remembers to put John at ease about his absence, knowing that despite the progress they've made lately, going AWOL is still a bit not good after everything that's happened, John decides to ignore the irritated huff that accompanies Sherlock's words, and nods his assent to Sherlock's keeping-in-touch plan.

He watches as the detective slips into his coat and pockets a few items that, to John, seem completely random, but are no doubt connected in some grander scheme – a kitchen spoon, a Christmas cracker left in the flat by Mrs Hudson over a year ago, a microscope slide, a pocket-edition of Botany Basics, a travel manicure set, and...

"Sherlock, no." John warns as Sherlock reaches for his emergency cigarette pack.

"But John..."

"No. You're just playing junkie, remember? You're not actually going back to an addiction of any kind."

For a few seconds their eyes lock in a battle of wills, but eventually Sherlock theatrically drops the cigarettes onto the seat of his black leather chair and stomps into the kitchen. John follows, a victorious smirk etched onto his face. A few more things find their home in the depths of the Belstaff – a sowing needle and a spool of John's surgical thread, a set of plastic dominos and a pack of coloured metal paper clips – and then Sherlock's tying his scarf, about to leave.

"Urm...ok, well...any last instructions?" John asks, unsure how to act. Saying goodbye seems both too plain and too ominous, but anything more just isn't fitting. It's just another case. They've done this a million times.

"Keep in touch with Lestrade, in case any new bodies turn up. I will try to stay up to date, but two sets of eyes are better than one, even if the other set isn't mine."

"Lovely, ta for that."

"Yes, well...I'm off then. I'll be in touch. When I get my hands on a sample, I'll find a way to send it to you, so you can take it to Molly for analysis."

"Ok."

"It shouldn't take long to solve this...one can't even count on drug lords to be creative these days."

"Yeah, well, I can't really say my heart is bleeding because of that. Got everything you need?"

Sherlock smirks at John, a slightly manic light illuminating his eyes.

"A case of mysterious deaths in the underground junkie network cause by untraceable poisoned drugs, with victims cropping up randomly, in unconnected parts of London, with no obvious pattern? Yes, I'd say I have everything I need."

It's so very improper, morbid, and John knows it, but he still finds himself fondly shaking his head and hiding a smile as he watches Sherlock bounce down the stairs and out of the door. The door-slam sounds like a match being struck, a spark of that special case-related energy finally and John can almost see the blaze trailing behind Sherlock as the imposing figure in a billowing coat (always so dramatic, John thinks) summons a cab out of thin air and disappears from John's sight.

It's early December and the days are growing short, snow twirling outside the windows. As shadows start to slither over the floor, John walks over to the fireplace and pokes idly at the items on the mantelpiece. He looks back at the screen of Sherlock's laptop, eyes trained on the sallow, waxy face of the dead girl, her eyes open wide and glassy, her arms littered with needle marks, like little pores opened wider in the skin to allow life to slowly seep away and escape the abused shell of a body that contained it. He thinks of dirty underpasses, foul-smelling alleys and wind-whipped squat houses, and of Sherlock going undercover as a relapsed junkie. Sherlock is the master of disguise, John knows this, so he knows he doesn't have to worry about Sherlock nailing his cover...but just as a woman (The Woman) once said, every disguise is really a self-portrait in the end. So, John doesn't really worry Sherlock will have a problem fitting in – he's afraid this particular self-portrait will be a bit too easy to paint.

Knowing that no use can come from such line of thinking, John averts his eyes from the picture, and busies himself at the hearth. His movements are precise and calm, practiced, and everything seems in perfect order – everything is in perfect order – which is precisely why John tries his best to ignore the mental image that slowly morphs from the dead girl to a dead Sherlock, splayed in the same way over a dirty patch of asphalt, and lights the fire.