Pairings/Characters: Sherlock/John, Mycroft/Lestrade, Anthea, Mummy, miscellaneous Sherlock folks

Warnings: AU, mythological creatures, gore, angst, mentioned drug abuse, eventual SPOILERS for series one and two

Disclaimer: Sherlock Holmes and all his friends, arch-enemies, and relations belong to me only in the sense that I own a copy of his books. Any and all scribbles I make about him et al are only profitable in the sense that it makes me happy, much as playing with stuffed animals made me happy when I was six.

Summary: Sherlock figures out that the mate to his wolf is John Watson. And that's just the beginning of his problems.

AN: This is un-betaed and un-Britpicked, so all errors are mine. Please point out any that you see! Title taken from "In This Twilight" by Nine Inch Nails. I don't expect the rating to go up, but there will eventually be extensive spoilers for season two as it is season two's fault entirely that this grew from a nice little one-shot to a story with chapters.

It was inevitable really, which is why Sherlock is so disgusted with himself when it finally happens. All the warning signs were there, but he'd tripped past each, so blindly sure was he that he had this whole instinctive thing under control. He'd carelessly assumed that simply because it hadn't happened before, that there was no danger of it happening now.

This is why he so hated exceptions. They always disproved the rule.

John Watson certainly hadn't looked or smelt or seemed like an exception on that winter's day at Bart's, and Sherlock had been intrigued and delighted when John proved exceptional the next evening, saving Sherlock's life in the process. The signs had all been there. He'd willfully ignored them.

As long as he'd been alive, he'd been with the wolf and the wolf with him. Their storied bloodline was immensely powerful, one of the purest modern lineages in the Old World, untainted by the inbreeding that had brought other Clans to their knees. Sherlock and Mycroft had been born into their heritage, full shifters from infancy, while most shifter children had to undergo the Change in their teens if they ever wanted to tap into their full potential. Despite the vicious whispers that the Holmes line was polluted with half-breeds and humans, no other Clan of the modern age could boast the sheer quantity of full shifters that existed within the extended Holmes family tree.

The secret of his Clan's success was simple, if at one time quite scandalous in the eyes of the other Great Houses. The Holmes Clan believed in mating by the instinctive pull of one to another – often romantically referred to in the packs as "the Song" – instead of making social and political alliances as so many of the other Great Houses were wont. Sherlock's paternal grandmother was from a mutt-pack that carried strong genes for birthing full shifters, while Mummy hailed from a powerful French Clan that – while small in the wake of revolution and war – still controlled nearly sixty percent of Gaul packs.

Sherlock and Mycroft had been taught from an early age how to control their wolves, how to guard against sycophants and climbers, wolves who wanted to be grafted into the Clan or even into the intimacy of the Holmes' family pack. The boys learned to use their senses offensively, how to hunt in both sets of skin. Father taught them how to shift at will, how to use their ears and eyes and noses, how to let the wolf ride close under their human selves and vice versa. Mummy took them to her Clan on summer breaks to expand their education with the secrets of the Vernet Clan.

When they were of age, they were taught how to breed without mating, how to scent and how to resist being scented, and – most importantly – how to identify their Song in another, how to find and claim their chosen mate.

Mycroft was like a sponge, he and his wolf taking to every lesson with focused intent. They wielded their senses as weapons, manipulated scenting so that it smoothed their way in the treacherous waters of human politics, and lightly dodged every attempt to rope them into a poor mating.

When Mycroft did take a mate, it was to a shiftless divorcee, a descendent of a small French pack that had dissolved at the time of Napoleon. It caused a minor sensation in the ranks of the Great Houses, though the Holmes Clan itself unanimously approved of Gregory Lestrade. There was talk for a time of the line of succession being in question as the heir had mated with another man, but the talk had petered out when the news that Mycroft and his mate were considering suitable surrogates in the Holmes Clan was deliberately leaked.

Sherlock was no less clever a student of his wolf's abilities, but the topic of mating he found unbearably dull. It was the sheer luck of his Song being so convoluted and unique that kept him safe the first few times he was approached by ambitious wolves of other Clans looking to get a leg up in the world. After the scare with Sebastian in uni though, Sherlock began to take the subject a little more seriously, even if it was only for the purpose of actively avoiding another such entanglement.

He self-medicated to get through the heats, he stopped shifting with the moon, he learned to cool his scent to a level at which it was virtually impossible to detect, and while he used his senses for his work, he effectively buried every other aspect of his wolf under layers and layers of mental shields. Sherlock became determined to override the pull of instinct with unrelenting logical reasoning, and he succeeded for the most part.

Until John Watson.

If there was wolf in the Watson bloodline, it was such a small trace as to be virtually nonexistent. John smelled interesting but not quite like Blood. John didn't seem to observe wolf custom or behaviors, behaved in ways clearly opposed to Clan protocol – not that Sherlock minded very much about that himself.

And yet, John was a creature of instinct, fiercely protective and unabashedly visceral in all his doings. Even in the first full day of their acquaintance, John had behaved as though Sherlock and he were pack. Suspicious of outsiders, loyal to a pack-brother to the exclusion of all other input, joining a hunt and contributing where he could to close the net, and finally displaying a willingness to close his teeth around the throat of an enemy of the pack. John Watson did not smell like Blood, but Sherlock had never seen a man in whom the wolf seemed to shine more brightly.

So when Sherlock realized that there was another voice coming forward in the harmonies of his Song, he was disgusted with himself for not having seen the implications sooner.

There were worse mates to be had; Sebastian for one. But John wasn't wolf and Sherlock had spent so much time pretending he wasn't either that he was at a loss for how to deal with this sudden change in how he thought of his friend. For one thing, John was on the prowl to breed, to find a human mate for his own. Sherlock's wolf did not find this concept amusing and seemed daily to be growing more immune to the chains and barriers Sherlock tried to throw in its way. The wolf was waking up from its sleep, no longer content to let Sherlock run things his way, and Sherlock could not remember a time when he and his wolf were less in harmony. Of one thing Sherlock was absolutely certain: if he didn't find a way to turn his mate's eyes toward them, the wolf would make it happen, damn the consequences.

When John's Song first spoke for someone, he was a broken shell of a middle-aged man, bereft of health, career, and hope. That the Song had spoken for a strange, chaotic, brilliant man he tentatively thought of as new flatmate either made the situation infinitely better or worse; he couldn't decide. What he found out in the first few weeks of acquaintance made him devotedly attached to his new friend, but absolutely terrified of his potential mate.

Sherlock was Blood, the European kind. Not only that, but Sherlock was second son in the primary line of one of the Great Houses. Sherlock was Clan royalty, whether the consulting detective liked it or not.

John's family was relatively new to the Blood, and were decidedly not from the old European lineage. His grandfather received the Change in the trenches near the end of the Great War, from an American whose father had left Brazil with only a suitcase and a curse to his name. The Blood Hamish Watson had received was so dissimilar to any found on the Continent that most of the Clans in Europe and Asia did not even recognize it when they smelled it or saw their Change. This obscure Blood was ancient but odd, and everything from their smell to their behavior was disparate to the known Clans.

So the Watsons had kept their strange new heritage a secret, had kept away from the Great Houses and the packs they ruled. And everything had been fine. They'd lived as they could, Changing when the moon called, Singing with their unruly pack, and occasionally lying low when a farmer reported a strange fox appearing for late-night prowls through the surrounding countryside.

Until John Watson's Song had called for the wolf in Sherlock Holmes.

It hurt, like a something hard and rough was being tossed about inside his chest, for the first few weeks to act as though he didn't know, didn't feel his new flat mate's presence under his skin like a physical ache. But for all the degrees to which he did give in to the intimacy of living (and working) with Sherlock Holmes, it was the most powerful sense of rightness that he had ever felt. The relief of belonging again drowned out the need for more, the need to press close and search out every facet of Sherlock's scent across the gangly sprawl of unexpectedly graceful limbs. The need to touch the webbing between those dancing fingers and investigate the soft skin of an unseen belly. The need to complete their Songs and resolve the hanging melodies that strung out between them.

John hadn't really had a pack since his parents' deaths. He'd sought out something akin to that purposeful sense of camaraderie and comfort in the Army when Harry had married Clara, established her own pack that no longer had a place for her kid brother. Not that Harry thought of Clara as pack. Harry was John's proof that a wolf could live without its mate, after all.

Harry's mate was a girl she'd met when they'd all been kids. Dahlia and Harry had been thick as thieves, right up until Dahlia's parents had sensed their daughter's Song changing. John didn't know what Dahlia's parents found most abhorrent about Harry: that she was a girl or that she wasn't, so far as they knew, wolf. What he knew was that he'd never heard his father's raised voice until the night that Dahlia's parents came over to inform the Watson family that Harry was never to have contact with Dahlia again when they sent her away to a boarding school.

Harry tried, John knew, to keep it together, living on the promise of Dahlia's return when she was no longer subject to her parents' control. Their own parents had tried their hardest to insulate the pain of Harry's separation, to soothe her loss. But during Harry's second year of uni, there had been the accident. John had been forced to stay with a mate's family for those last few months before heading down to London for uni himself. Harry hadn't been so lucky, so far as he could tell.

And then, barely a year later, Harry had shown up in London, a handle of whiskey and a newspaper clipping in hand. When he'd finally pried them out of Harry's hands, lax in drunken slumber, John read the newsprint in quiet horror. Dahlia had married a young lord the week before.

That Harry loved Clara, John knew. But he'd also known, standing there in his fitted suit, giving away his elder sibling at her wedding, that Harry was fundamentally broken. Harry would never be wolf again. John's pack was all dead.

He'd run for the recruiting office the very next day.

And now here he was, on the rough side of thirty and shattered apart inside and out, back in London and witness to the further implosion of his sister's mind. His wolf snapped out, conscious of its injuries and weaknesses, bitter and lonely and full of a nameless longing sorrow. And that last little bit of hope that secrets and loss and Afghanistan hadn't managed to kill yet.

Sherlock Holmes, his wolf sang, deep and joyful in his chest. Sherlock Holmes.

End Chapter One

AN #2: Sherlock (and all "European" wolves and their Clans) are based off of the gray wolf (Canis lupus), which was at one time indigenous to pretty much the whole of the northern Hemisphere. John (and the Watson family) are carrying Blood from a different genus of Canidae family, the Maned wolf (the only member of the Chrysocyon genus) which is indigenous to Brazil. They look a little bit like a large fox and have a distinctive odor (thus the confusion of scents to the gray wolves he's surrounded by). More on his Blood later, but you can read up on maned wolves here: (.org/wiki/Maned_wolf) I'm not going to be too terribly literal overall when it comes to Maned wolf behavior versus Gray wolves or get into a whole lot of genetic mumbo-jumbo, as pretty much everyone is walking on two legs in the human world most of the time, but I wanted to settle any confusion about John's wolf now before things get confusing.