If the platform and train were exhilarating, Hogwarts was everything Sherlock had imagined, and more. If he'd had a sense of romance it would have begun and ended here: in this castle of mighty stone battlements, soaring arches, intricately paned windows that sparkled like diamonds in the starlight, and tall spires reaching to the star-streaked heavens.

And Sherlock did have some sense of the majesty that induced his classmates to break into murmurs and several low whistles as they approached the castle across the lake. It was clear that even those who had been raised on stories of Hogwarts had never seen it before in person. But he found it impossible to focus on the grandeur of the scene before him. Questions reeled through his mind like ticker tape, too rapidly to formulate even theoretical answers to the better part of them. Sherlock squeezed his eyes shut briefly against the candlelit luminescence spilling out of the castle and reflecting off the water. If he didn't categorize, now, it would be an evening of barely-contained overwhelm, maybe even panic, instead of information-gathering. And that simply would not do.

Belinda, distrusting the edges of the boat, leapt gracefully into Sherlock's lap and began to purr. The sound drifted across the silent lake, and Sherlock let himself relax into it.

By the time the little fleet of boats reached shore, Sherlock had composed himself - better indeed than the majority of the first-years, who were vibrating with excitement around him. It was very simple, he told himself. The two categories to keep in his head, for now, concerned what was magically possible and why. The first, a mere list of the magical phenomena he encountered; for example, the way the boats propelled themselves across the lake. The second, his conjectures about the way these phenomena fit into the overall scope of magic. Sherlock reminded himself that this should eventually be converted from a series of hypotheses into a single, overarching theory that grew and changed over time. One could not make bricks without clay, nor should one speculate without facts. And how-that would come later, in classes. Tonight he would content himself with mere observation.

At no point did it occur to Sherlock that the most fruitful short-term observations might concern the other inhabitants of the castle rather than the system of magic itself.

The real question that was tormenting Sherlock, and had been all summer, was whether magic ought to be defined as an offshoot of some other branch of energy, or whether it was something altogether more fundamental. Gravity, electromagnetism, and the strong and weak nuclear forces, he knew, are the four forces that determine the goings-on in the universe, with the latter two discovered less than a century before. Perhaps magic was a fifth, the quintessence hypothesized by physicists. Or perhaps it was simply an unrecognized consequence of one of the others.

At eleven years old, Sherlock's only form of self-awareness came from the usually adverse reactions his behavior caused in others: the Dursleys, his teachers, and one or two aborted attempts at friendship. He had in no way begun to turn inward the intense scrutiny he applied to everything else. His was the vague perception of schoolboy archetypes that all children acquire in primary school, through books and television and peer interactions. For a long time now those interactions had been rare, and so Sherlock's introspection extended only to the self-applied labels of intellectual and inveterate annoyance.

He was unaware, for example, and would not have admitted had he known it, that his speculations on the nature of magic were driven by a motive far less lofty than understanding the cosmos. He was about to gain some inkling of this, however.

Sherlock had realized the instant he saw the castle on the cover of Hogwarts: A History that wizards were not going to drop the medieval theme, now or ever. His school-his home for the next nine months, at least-would be more traditionalist even than Eton. The realization made him roll his eyes. Sherlock had a somewhat suppressed eye for beauty, and no appreciation at all for aesthetic.

But it was different in person.

Sherlock stood before any of the others, the moment his boat nosed against the sandy shore. For a moment he balanced on the wooden seat, a thin dark silhouette against the brightly lit castle. As Hagrid struggled out of his tiny boat, Sherlock leapt lightly onto the sandy shore. He craned his neck back to look at his new home. And caught his breath.

Gothic, magnificent, it towered over him. Arches and battlements, wide limestone steps, a great iron-banded door that belonged in a medieval monastery. Stone walls, thicker than he was tall. And the whole thing was lit with a warm, blazing light, seeping out of high windows and from beneath the door. Had Sherlock been of a mythological turn of mind it would have seemed, glowing on that moonless night, a sort of Shangri-La, a Valhalla, an afterlife into which, like an ancient Greek, he entered the moment he stepped off the boat. To judge from their hush, many of the other students did feel that way. But in Sherlock the reverence was replaced with apprehension. A sense of imposter syndrome so acute it nearly knocked him off his feet.

Faded, oversize jeans- a few sharp words- a beating over burnt bacon- those were what belonged to him, what had always been his lot. This was something else; something out of the book of fairytales that Mycroft had once received as an ill-advised birthday gift and that three-year-old Sherlock had read on the sly.

He remembered it seldom, having turned his mind from there to piracy and then to science. But now the fantasy that had so briefly engrossed him in toddlerhood came rushing back. Here, there could be dragons.

But could he really be here? Was there any way that anyone born to the right of this castle and its secrets would look at him, Sherlock Potter, and not see him for what he was: the boy from the cramped cupboard, the worthless and unwanted orphan on the doorstep? It was written all over him-hand-me-down sneakers with frayed laces, unobtrusive posture, a slight favoring of the bruised shoulder where Uncle Vernon had pressed down while breathing his last threat before leaving the house.

Again Belinda was there, wrapping her furry length around his ankles in a comforting weave. Not for the first time, Sherlock wondered whether she could read his mind.

He took a breath, squared his shoulders to match his upturned head, and the flurry of self-doubt melted away as quickly as it had come. No one is anything but what he makes of himself. Aunt Petunia and Uncle Vernon always had everything I did not, and they are stupid, shallow, and close-minded.

Besides, Sherlock had always found ways to take what he needed. He would do that here, too.

He bent to retrieve Belinda's warm weight, adjusting so that her paws rested comfortably across his forearm. He looked down into her green eyes and blinked slowly, as had become the greeting between them.

Soon, every secret of this castle will be yours and mine.

The grounds were silent, waiting, watchful.

Only the soft ripple of wavelets against the sides of the boats and the exhilarated murmurs of a couple of first-years brushed Sherlock's ears, as lightly as the early autumn breeze that still carried summer on its breath. At length Hagrid succeeded in extracting his cauldron-sized boot from the rowboat, and commenced to lead the way up the steps. Sherlock held back, eager for a last look across the isolated grounds. But the rest of the first-years gathered in a tight clump around Hagrid, like chicks around a mother hen, as he reached the door and took firm hold of the heavy iron knocker.

Boom. Boom. Boom.

The knock reverberated through the castle, and Sherlock was briefly caught up in a bizarre memory of the Three Little Pigs, and this must be why they built the place of stone-

And then the door opened, the spell was broken, and a tall, black-haired witch was explaining in strict tones what was to be done when they reached the Great Hall.

Really don't know why I haven't deleted those fairy tales, Sherlock thought to himself, shaking his head as he followed the others inside.

It was a blur, a sensory overload akin to Platform 9 ¾ or Diagon Alley. Moving portraits, floating candles, ghosts-

Bright banners in red, blue, yellow, and green, draping the walls and hanging down from the ceiling, which was not a ceiling but an indoor extension of the cloudless, starry sky-

Echoes of footsteps on stone, scores of eyes and heads turning toward the first-years, tantalizing smells of food, though none was yet in sight, golden plates and cups polished to a shine, and well over a hundred voices carrying on lively conversations.

The noise died down a bit as the first years entered. It was small relief. In the next few seconds they were ushered down a walkway between four long tables, toward a raised dais at the end of the cavernous hall. A sort of high table sat behind a golden podium, looking to be inhabited by the school staff. Sherlock caught the eye of a beaming, silver-bearded wizard in deep purple robes, and recalled, with a sudden shock, what Hagrid had told him about the night his parents died. It was the headmaster, this Dumbledore, who had left him on the Dursley's doorstep.

Why?

Sherlock was distracted the next moment by a hideously sharp twinge in his scar that brought his hand to his forehead involuntarily. Instantly, he regretted it. His eyes had wandered in his contemplation of Dumbledore's motives, and he found himself now locked in an inadvertent staring contest.

The opponent was tall and dark-eyed, with stringy black hair and an unhealthy cast to his pale skin. He looked as though he belonged someplace wet and damp, with other pale and slimy things. Sherlock's first impulse was to throw him in the lake and his second was to break eye contact, but some instinct deeper than thought warned him not to show weakness in front of this man.

What do you teach? Sherlock asked him silently. Necromancy?

Sherlock's thoughts would have been a little less flippant had he known what the man was capable of, but Severus Snape got the message loud and clear even without employing Legilimency, the use of which was forbidden on students.

Both were distracted when a battered stool and an even more battered wizards' hat were produced from somewhere. The shock of the first years when the hat opened its flap and burst into song soon subsided, in Sherlock's case, into cringing. Magical the hat might be, but it was also remarkably tone-deaf. He looked around for Belinda, who had sprung from his arms in order to explore when they first entered the hall, and spotted a reflective pair of green eyes peering from beneath the high table. McGonagall gave a few terse instructions, and the Sorting began.

Every Wizarding School has its own methodology for student organization and excellence, and each considers its own traditions superior to all others. Wizards, though clannish also by virtue of magic, have no more succeeded in bridging the divisions of nationalism and culture than Muggles have. Therefore it is a matter of British pride as well as practicality that every eleven-year-old witch or wizard take their seat beneath the ancient Sorting Hat of Godric Gryffindor.

Sherlock had no more fondness for tradition than for any other rules he deemed arbitrary or restrictive. But his personal tenet for the night was to observe rather than act, and so he watched with interest as his peers were called up, one by one, in alphabetical order. He made a game of it, trying to guess by their bearing (and the comments and behavior he had observed on the train) which House they would be Sorted into. Fortunately he had more to guide him than the brief descriptions of the Houses in the Hat's song. His discussion with Hagrid about Voldemort had led to a discussion of Slytherin House and its reputation, and thence to descriptions of the other three Houses.

Sherlock guessed the right House a little more than half the time. Some of the students surprised him. One plump boy with a fearful face, (whom Sherlock recognized as the owner of a toad he had rescued from Belinda on the train) went with wobbly knees to the Gryffindor table. So did a bushy-haired brunette who had spent the evening whispering factoids from Hogwarts: A History to anyone who would listen. Others were easy to guess: a smirking blond boy whose every movement screamed pureblood! was assigned to Slytherin the moment the hat touched his head.

When Sherlock's name was called, silence fell. Then a crescendo of excited whispers rose.

"Sherlock Potter!"

"-Boy Who Lived…"

"Is it really him?"

"...reckoned he'd be taller…"

"Do you see his scar?"

At Professor McGonagall's sternest look the noise subsided, but Sherlock could still hear murmurs as he passed. Even the remaining first years had turned aside in awe, looking over their shoulders, and when the scrawny black-haired boy made his way forward they parted before him like the Red Sea.

Doing his best to avoid eye contact with the crowd, Sherlock allowed his feet to direct him to the battered hat on the old wooden stool and put it on. Not without a few reservations, which intensified when the hat slipped over his eyes and left him in darkness. Sherlock did not like to be deprived of his eyesight, particularly not when a whole hall of strangers was observing him.

In order to shed light on the Sorting Hat's impression of the child beneath it, and their subsequent interactions, it is necessary to step away from our hero for a moment and examine the history of the Hat itself.

The hat of Godric Gryffindor was one of the earliest and still the most advanced example of the strangest of the transfigurative arts: producing sentience in a formerly inanimate object. The methods Gryffindor used have in fact been lost and only partially recovered from the scattered notes of Helena Ravenclaw, whose mother aided in its development (that no extant writings remain from Rowena herself is considered a loss on par with the burning of the Muggle Library of Alexandria).

The Sorting Hat has, therefore, a mind of its own, and moreover is aware of the fact-a level of sentience unmatched even by most nonhuman animals. In intellectual capacity it is as far from the shouting toasters or charmed carriages in common Wizarding use as a parrot is from Archimedes, although like the parrot these lesser animations are capable of carrying through pretrained commands and sometimes even conversation.

Wizards have other methods of producing sentience, but these are not purely fabricated-not transfigurative. Generally they involve transplanting a ghostly imprint of personality, or in some cases a portion of a soul, into an inanimate object. The latter can only be achieved by Dark means.

And some say that the Sorting Hat, when charged with the protection of Hogwarts, was inadvertently imbued with a portion of Gryffindor's own personality. Lacking a biological neural network, however, it possesses none of the physical or emotional needs of other consciousnesses. It thinks a great many things and keeps most of them to itself, and although incapable of emotion beyond intellectual enjoyment is generally benevolent.

The Sorting Hat has, unsurprisingly, been an object of intense study to scholars in centuries past. Most ask it questions of historical import, which the Hat, itself brought into being by a man of didactic ambition, and knowing no higher good than the sharing of knowledge, answers without hesitation (but with more than a little pomp). Its scope is limited to the rumors and goings-on that have reached it during its long sojourn in the headmaster's office. All the same it provided many a clue to scholars eager to unearth details of magical history, especially as pertain to the castle. It is rumored that Dumbledore, in his early years as headmaster, allowed Bathilda Bagshot access to the Hat in order to aid her compilation of the definitive Hogwarts: A History.

One thing only the Hat holds sacred, and that is the topic upon which it is expert: the minds of those who take their places beneath it. Of the strengths, weaknesses, and peculiarities of practically every witch and wizard in Britain the Hat could say a great deal, but on this topic it keeps silent. By these the course of history is determined. The Sorting Hat, consummate observer, wishes to determine nothing save the Houses into which the students of Hogwarts are Sorted.

Most who pass under its brim give no thought to any of this. They are too young, too nervous, too self-absorbed. Sherlock's active mind would have presented an exception (and indeed would give the matter a great deal of study when he had the leisure), but at the moment he sat down Sherlock was not thinking of magical theory at all. There was too much to process. His brain was in overdrive, working so quickly he felt that it would vibrate out of his head, Hat and all. Sights, sounds, smells, the strange hatred emanating from the black-haired professor, the concurrent pain in his scar-

Coincidence-?

And then blackness.

The Sorting Hat peered through Sherlock's mind with the delicate touch of a connoisseur. It was a mind both more and less unique than might be supposed. The boy had not had an easy life. No more would he have an easy future. There was resentment, and a conscious disinterest in the resentment; a dislike for abusive family members that held too little of his attention to blossom into hatred. There was courage that Sherlock himself did not suspect, and of which the Hat chose not to inform him. Such things are learned in time. There was a subtle yearning for parents and past that ended in a curiously blank wall. There was a complex tangle of emotion toward someone whom Sherlock considered more fortunate, astute, and manipulative than himself. A refusal to examine himself in the mirror of that individual. An almost total lack of regard for the rest of humanity.

This came with more than a little arrogance, though it was rather that of the intellect than the bourgeois. No regard at all for class or appearance or any of the usual subconscious undertones of prejudice that are present in larval stage even in children.

And then, of course, there was the intellect itself.

The Sorting Hat had been most amused when it learned of the Muggle concept of IQ tests. How tedious-how one-sided! And yet, with the progression of the twentieth century it had slowly become fascinated with the Muggle art of "science". Limited, yes, but how practical when one lacked the magical tools to simply delve into the consciousness, or the nature of the universe. The tendency to quantify was a peculiarity the Hat had frequently noted in Muggleborn students, and though it was still fuzzy on the intelligence scale Muggles used, it thought Sherlock's mind a match for any it had encountered before.

And Sherlock's intellect was fueled with intense passion-a thirst for something that he had not found yet. A focus. The churning, whirling gears of this mind would tear themselves apart like a rocket on the launch pad if it did not find application for all it took in.

At this rate he had a few years before madness set in, the Hat estimated. Best to set the lad on the right road as soon as possible.

Because the Sorting Hat understood that for Sherlock Potter, comprehension of the ultimate mysteries (magic, physics, and everything in between) comprised a means rather than an end. Sherlock Potter did not care for knowledge; he cared for learning. No, not for learning: for finding out. He was not an intellectual, content with stores of facts; he was not a teacher, interested in sharing them; not a student, patiently awaiting their presentation. He was an artisan, concerned with crafting knowledge. The difference was that chefs, carpenters, and painters create with their hands, whereas Sherlock created with his mind. Also, he delighted but briefly in the completed masterpiece. Pulling bits and pieces together and drawing an unknown firmly into the region of the known-there was his enjoyment. A mystery when no longer mysterious was unimportant; a solved matter no longer mattered. Things already known and the applications to which people put the new knowledge he dug up were of interest only insofar as they furthered his own investigations.

Sherlock suspected none of this about himself. Had he not spent his lifetime learning, experimenting, devouring Mycroft's books? It was his only refuge. What respect, what value could he ever gain except by knowing more than other people did? And what pleasure, what revenge could be derived on those older and more powerful without demonstrating, as he did to Petunia and Vernon, that he was their natural superior in matters of the mind? That he lived on planes they could not dream of? Why suffer the effects of fury that he himself had not had a hand in creating?

The closest Sherlock came to understanding this was in his magical ambitions. Physics was interesting in theory, but magic was interesting in reality. Mix the right ingredients, add the right stimulus, and achieve reactions that you can control. Magic was like chemistry-magic was chemistry, imbued with wider possibilities. The better he understood its fundamental workings, Sherlock reasoned, the more effectively he could manipulate it to his own ends.

Magic was freedom, and the ambition was not achieve greatness, help humanity, or gain understanding. The ambition was I do what I want to, and no one ever stops me again.

Sherlock sat beneath the Sorting Hat for long minutes in silence. Conscious of the concentrated gaze of the entire hall, he sat straight-backed and did not fidget. Sherlock had two methods of thought. One involved pacing, gesturing, and throwing out random phrases at whomever was near. The other left him sitting, lost and immobile, for hours.

To avoid thinking about the eyes, he forced himself to adopt the second.

And to avoid thinking about the violation of his private thoughts, the suspicion of which had grown as he saw his classmates Sorted and which brought his heart to his throat in fury, he forced himself to focus on the nonvisual sensations in the Great Hall. He picked out and predicted the dishes that would be served, though there were too many to count, and many he had never tasted. The blended smells eventually made him nauseous, and he switched to identifying the directions from which came the occasional cough or sneeze in the silent hall. This was no easy task, as the sounds echoed off the stone walls, and Sherlock's concentration on these subtle sounds was so intense that he startled when at length the Hat spoke in his ear.

"At long last, young one. The Boy Who Lived meets the Sorting Hat. Odd titles both."

Sherlock's relief from the suspense made him sharp.

"I didn't choose mine, though I'm not opposed to its basic implication."

"Your peers live and breathe as you do," mused the Hat, "and for the most part sort themselves. Where would you place yourself, I wonder?"

"Whichever House has the lowest concentration of idiocy. If you don't have one of those, I'm capable of making do."

"Such high tolerance for your peers."

Sherlock missed the Hat's sarcasm. Another bad habit it was picking up from modern teenagers.

"Tolerance?" he sounded surprised. "No, I don't require peers to function. All they've done since I got here is ogle at my forehead. I'm implying that you can skip the House entirely. I'll make do."

"Not part of the program, I'm afraid."

Sherlock clenched his fists.

"In that case, I've run the quantitative idiocy statistics for you. Ravenclaw would be all right."

"Predictable," said the Hat in his ear. "All those libraries and reading. Boring, surely?"

"Libraries and reading are useful," said Sherlock rather irritably; he had never before been accused of predictability. "And I will do what I like; I have no ambitions as a walking stereotype. You asked where I would place myself."

"And you just answered," replied the Hat, amused. "Now, would you like some advice?"

"Is that how this generally goes?"

"You are incapable of half measures. When you choose a path, you will follow it to its end. Be very careful when choosing. And when you do, dive deep and do not resurface. You are one who can only breathe in deep waters."

"You're mixing metaphors."

"Fight disorder, but not obsession. You will need it to guide you since you refuse to be guided by anything else. Learn yourself and then learn others. Accustom yourself to pressure, Chosen One, or your mind will snap like a twig."

Sherlock's carefully fabricated balance was gone. He sat disoriented, murmurs washing over him, with no thought now of localizing them but aware that they were growing louder the longer he sat. Did the Hat give this lecture to everyone? No wonder they were shaking as they went to their places. That plump Gryffindor boy hardly made it to his seat. But no, it couldn't be...most of the first-years had slid off the stool within seconds...had the Hat actually implied just now that his mind was inadequate? Sherlock's?

But what came out, instead of indignation, was, "Chosen One?"

"Another path you have not finished walking," said the Hat cryptically. "Extraordinary minds lead extraordinary lives. Or don't. That is why I caution you to prepare yourself. But this is all rather heavy for an eleven-year-old. I would refrain, but I never can know if we'll meet again."

Then the Hat broke its rule.

"One student I did meet again, at his insistence. An information-seeker for his own ends, like you, but unlike you courteous to a fault. He thought of the soul as something separate from the mind, and so he didn't think I would sense that at our second meeting he wasn't all there. What is partial cannot be wholly destroyed. But I think you will find that wholeness is still worthwhile."

"But my House?" Sherlock asked croakily, as each word was subconsciously filed away. "You said that students Sort themselves. It's my choice, then?"

"The choice is always yours, Sherlock.

Slytherin!"