Harry makes his way down to breakfast with Blaise and Theodore the next day, and Harry tells them (without mentioning the cloak, of course) what he'd heard the prefects planning the night before. Theodore nods his head in obvious approval, liking the idea of having a library immediately to hand.

"Do you think it will have the same restrictions to content as the main library?" Blaise asks thoughtfully, "Draco's father has been trying to have some texts added to it for years now."

"It depends on if Dumbledore is in charge of overseeing the list, or if Snape is," Theodore replies, frowning slightly. "I don't think there's much of a loophole there, though."

"Good," Harry says, "I looked up some of the books he's mentioned, and no one needs books like that in a school. If people so desperately want to read some fantasy story about how Muggleborns are the end of the society, they can buy their own copy." Blaise frowns at him.

"They're just facts, Harry," he says, and Harry sniggers, shaking his head. He doesn't even bother to start the argument this early in the morning; he's not really willing to entertain anything that says Jon and Peggy Granger are any kind of threat to the wizarding way of life. Besides, his mum was Muggleborn.

"Yeah, Blaise, sure they are," he says sarcastically: Blaise's lips purse, his eyes narrowing in obvious anger, and he gets ready to argue, but they stop short just before entering the entrance hall. There are two wizards in deep, purple robes, and beside them Harry sees a photographer, looking at the film in his camera. "What the Hell are they doing here?"

"You discovered a secret library that might have been built by Salazar Slytherin himself, and you're surprised the press is going to report on it?" Theodore asks, and Harry groans. He hurries towards the great hall, just wanting to get in and have breakfast, but a hand grabs tightly on the collar of his robes.

"Harry!" Lockhart proclaims, pulling him around. The reporters latch eyes on him, and Harry tries to pull himself free as they come forwards. "Why don't we have a photo together for the Prophet?" The photographer is raising his camera, so Harry stamps down hard on the toe of one of Lockhart's pretentious two-tone shoes, and Lockhart lets Harry go as he cries out. Harry runs into the great hall, moving to sit down between Hermione and Parvati Patil at the Gryffindor table.

"Got confused, did you?" Parvati asks.

"There are reporters that want to take photos of me," Harry says, and Parvati stares at him perplexedly, obviously not understanding why he'd want to avoid that sort of press attention. "Right, Hermione- You've heard how I'm a Parselmouth?"

"Percy was explaining it this morning," Hermione explains, nodding her head. "That's so interesting, Harry, you know there hasn't been a known Parselmouth at Hogwarts since-" Harry feels that if he lets Hermione continue this train of thought, it will be difficult to get any words in edgeways, so he simple talks over her.

"I found a secret library in the Slytherin common room." Hermione's mouth freezes mid-infodump, and she stares at Harry, looking as if four birthdays, two Christmases and Flourish and Blotts' mid-February sale have come all at once.

"Oh my God!"

"There aren't any books in it," he tells her quickly, and her face falls.

"Oh," she says, less excitedly, "But you found a secret library?" Harry explains as they begin to eat, and for the most part the Gryffindors just ignore him - occasionally, Colin Creevey will crane his neck to try to catch Harry's eye, but Harry does his best to ignore it.

"Hi, Harry," Ginny says brightly as she comes down to the table, and Harry smiles at her. "Did you make the right decision and swap houses?"

"Oh, damn, sorry, I meant to sit at the Ravenclaw table-" Hermione snorts, shoving Harry in the side, and Ginny lets out a little laugh, moving to sit with Creevey and some of the other first years further up the table. Now she's settled in at Hogwarts, Ginny seems much more confident and happy: most importantly, she no longer looks at Harry like he's some sort of mythical being that just walked out of the lake.

"She's doing pretty well," Hermione says, seeming to guess Harry's train of thought, and Harry nods his head. "She keeps messing about with the twins, teasing Percy - she's really enjoying it here, and she's even learned a few jinxes." Harry pokes at what remains of his scrambled eggs with his fork, settling into silence as he waits for Hermione to finish her cereal.

No reporters show themselves as they split up for History of Magic and Charms, and Harry forgets about them entirely by the time he and Hermione walk across the grass and settle down on a blanket. The grass is wet with dew, and even though the wind is a little biting, the sun is out and shining warmly on them. Professor Flitwick had told them there'd likely be snow tomorrow, but for the time being the sky is mostly clear.

"Serpensortia," Harry whispers, putting his wand forwards. Nothing happens. Hermione frowns.

"I think it's more like this," she says, and she sweeps her own hand forwards, "Serpensortia!" Her wand lets out a little hiss, but no snake bursts forth.

Harry flicks his wrist a little more: "Serpensortia!" The "snake" that flops forwards is blue, utterly limp, and rubbery. Harry picks it up, feeling it flop in his hands, and Hermione starts to laugh. He hits her with it, and she shoves him away from her, letting out a horrified noise at the thing's damp, gel-like surface and its texture: he lets out a laugh of his own, and then he turns, throwing the thing as hard as he can down the hill into the bushes.

Scandalized, Hermione puts her hand over her mouth, and Harry tries to cast the spell again.

---

Harry stares down at the photo of him and Hermione laughing together in the paper, lips twisted into a scowl. It's the new morning edition, and the animation shows Hermione and Harry laughing together: it's a nice photo, actually, and Harry's going to cut it out and keep it, but... He hates that it's in the paper. He hates that it's presented next to a photo captioned, Harry Potter's favoured mentor, Gilderoy Lockhart. He hates the whole tone of the article, which acts like he's done some phenomenally difficult thing by hissing in front of a doorway he didn't even know was there.

"It's a nice photo of you and Granger, at least," Theodore says, reading the irritation on Harry's face, and Harry nods his head. "You mastered that spell to cut things yet?"

"Nope," Harry replies, "Would you?"

"Sure," he says, taking the paper, and Harry watches the movement of his hands carefully as he trims around the edge of the photo, pulling it away from the paper. Harry takes it, folding it into his bag, and the paper itself he abandons on the table as he exits the room and makes his way up the stairs towards Transfiguration.

When he arrives at the classroom, McGonagall and Snape are talking outside of the door, and Harry hovers in the corridor, glancing between them. Snape gestures, silently, for Harry to follow him, and Harry sighs, reluctantly following his head of house down the stairs again. There's no sense in arguing, he's sure, and when Snape leads him to a gargoyle on the second floor.

"Liquorice All-Sorts," Snape bites out, and Harry furrows his brow at the strange password as the gargoyle leaps aside to let them upstairs.

"Liquorice All-Sorts?" he repeats. "What, does he like those?"

"Last month," Snape says despairingly, "It was Disco Discs."

"What's a Disco Disc?" Harry asks. It sounds like the sort of drug that centres in soap dramas in Muggle TV.

Snape arches an eyebrow, glancing at him, and then says, "It's the wrong name for a Dazzle Drop." Harry blinks at him, wondering what the Hell a Dazzle Drop is. They reach the top of the stairs, and Harry looks curiously around the room they enter as Snape walks forwards and towards the desk.

"Ah, Harry, you're here," Dumbledore says, standing from behind his desk as Snape sinks down into a chair, lips pressed together. He looks really annoyed, and Harry glances from him to Dumbledore, unsure of what's going on, but then he sees the other two people in the room. The first is a tall, black woman with deep, brown eyes and a short, neatly trimmed afro: the underpiece of her robes is lacy and white, but the outer fabric is a popping cherry red. The collar of the under robes is high, coming right up to her neck like Snape's does, but the outer robes are cut low in a V, showing most of her chest, and she wears black Muggle boots that seem incongruous with the obvious wizarding outfit. The man beside her is only a little taller than Snape, maybe 5'10", and his robes are a plain green: he has dark brown hair, and he's even paler than Snape, but in a way that looks healthy. His skin isn't nearly as sallow, for one.

"I'm here," Harry agrees, "Look, is this important?"

"No," Snape says.

"Yes," Dumbledore says. Harry looks at the headmaster sceptically, and Dumbledore smiles at him before he says, "Allow me to introduce you to Lindon Sartorius," the pale man gives a neat incline of his head, "And Cecilia Hayworth." The woman smiles at him, and Harry stares at the both of them before he glances back to Dumbledore, and then to Snape.

"Are you two, like, the real...?"

"The ones who wrote the books," Hayworth says, "Yeah." She's got an Irish accent. "I wrote An Introduction to the Wizarding World, which you might have been given when you were sorted?"

"I've got Catastrophes of the Recent Past, too. And then of course I've got Ministerial Insight and A Serpentine History, and I know you also wrote the introduction to the 1990 edition of The Heirs of Salazar Slytherin, Mr Sartorius." Harry can't help but feel surprised - wizarding academic books don't tend to have the descriptions of their authors, and he'd assumed that both Hayworth and Sartorius would be well into their eighties, but they're both only in their thirties, maybe approaching forty.

"Indeed, I did," he says quietly, with the same clipped, aristocratic tones the Malfoys, the Greengrasses, and the Zabinis use. Pureblood aristocracy, then, Harry guesses. "And of course, I am aware of your defeat of the Dark Lord as of 1981. Your best work, I should think." Harry laughs: it's rare that someone actually makes a joke like that to his face, and rarer still that the joke strikes him as funny.

"Ms Hayworth and Mr Sartorius are here, Harry, to investigate and examine the library in the Slytherin common room."

"We wish to locate artefacts and books that might have been buried somewhat in recent years, as well as to work out when this library was built, and by whom," Sartorius says, smoothing out on an imaginary crease on his robe, "We would like to utilize your unique talent, Mr Potter."

"Your Parseltongue," Hayworth supplies, "For the moment, we just want to look at the library, but after the holidays we'd like you to help us look through the castle, and use Parseltongue in front of certain snake symbols. If a Parselmouth could open that passage, others might be hidden around the castle, locked in the same way - it would have been a perfect method for Slytherin to restrict access to only himself and his heirs." Her eyes are bright, and she's visibly excited at the prospect: Sartorius, in contrast, stands with his hands behind his back and a neutral expression on his face.

Harry glances at Snape, who is watching the exchange with pursed lips and a disinterested expression, as if the two historians have come into Hogwarts to sell Harry a new brand of hoover. It sounds like a lot of effort for a subject Harry isn't extraordinarily interested in, and he considers downright refusing, but...

After an extended pause, Sartorius says, "We would, of course, pay you for your time, Mr Potter, and moreover, you would be credited with any relevant finds." Harry doesn't need the money, but the idea of being credited is intriguing, and there'll probably be other rewards. Not to mention, Hermione would probably murder him if he turned the opportunity down, and Harry's quite keen on surviving the year.

"Alright," Harry says. "Can I go now?"

"Of course, Mr Potter, but before you go," Dumbledore says, but first he holds out a bowl full of white-chocolate buttons covered in hundreds and thousands, "Would you like a Disco Disc?"

---

Harry watches Lockhart at the staff table that night, and he can see that he's somewhat put out at the whispers around the room. Some of them are about Harry himself, but the vast majority are about the new people sat at the end of the staff table, talking quietly with each other. New people at Hogwarts always raise a few eyebrows, especially new people under the age of 50, and Harry has already heard some of the older Slytherin lads talking about Cecilia Hayworth's backside.

Lockhart is making conversation with Flitwick, who seems to be doing his best to turn away and talk to Sprout instead, but Lockhart's heart isn't in his boasting tonight: he keeps leaning back to look at Hayworth and Sartorius, or letting his gaze flicker over the room to settle on the students who seem to be most focused on the two historians.

"What houses were they in?" Blaise asks Afifa Lanjwani as they make their way downstairs.

"Hayworth was a Ravenclaw, and Sartorius was in Slytherin," she answers. "They were in the same year as your father, apparently, Draco." Draco puts his chin in the air, seeming proud of this fact, despite his having nothing to do with it beyond blood relation, and Harry rolls his eyes.

---

Lucius Malfoy, when Harry writes him, is not forthcoming with information. He brushes the both of them off with a "I didn't really know either of them," but Harry is sure he must have at least known Sartorius, were they in the same set of dormitories at school, and he considers asking Snape about them, but he's aware that asking Snape any unacademic questions is usually a bad idea. Except for asking him about Disco Discs, apparently-

Harry looks up from his letter from Lucius Malfoy.

"Snape was raised by Muggles," Harry blurts out. Harry's an idiot, truly: he's seen Jazzies before, or Disco Discs, or Dazzle Drop, or whatever stupid thing you want to call them, and Harry knows they're not a wizarding sweet. Hermione looks up from her Charms essay, peering at him.

"Malfoy said that?"

"No, Snape did. He told me."

"I doubt he told me."

"Indirectly, he did." Harry sets his letter aside, explaining quickly, and Hermione takes it into account, nodding her head.

"I'm not surprised he's not forthcoming about it usually, Harry," she says lightly, "He is head of Slytherin house."

"He's friends with Lucius Malfoy," Harry says, folding the letter and dropping it into his bag to think about later. "It just seems weird that they're friends, if Snape's Muggleborn."

"You don't know he's Muggleborn," Hermione points out, and then he leans forwards, getting a better look at the library entrance. Harry follows her gaze: Lindon Sartorius' expensive shoes make barely any noise at all on the library's floor as he approaches Madam Pince, speaking to her seriously and keeping her gaze. Sartorius' eyes are a deep grey - not the icy colour of the Malfoys', but far darker, flecked with deep brown. Madam Pince waves her hand vaguely, and Sartorius nods his head, leaving the library again.

"What was Mr Sartorius asking about, Madam Pince?" Harry asks the next time she walks by, and the librarian huffs, shrugging her shoulders.

"Library magic. As if it's hard!" With that, Pince walks off again, and Harry and Hermione share a bemused look.

When Harry makes his way down to the common room that afternoon, after lunch, Sartorius and Hayworth are in the library, and Sartorius is making rough notes on a piece of parchment as Hayworth tells him, firmly, "This is a very stupid idea. I hope you realize that."

"My dear, it is not stupid in the least," Sartorius retorts in his smooth, silky voice, and Harry wonders if he does much public speaking. Sartorius is smug, and obviously a bit up in himself, but it's nice to listen to him speak, and Harry would be much happier to hear him drone on to them in History of Magic than he is Professor Binns. Hayworth puts up her hands, shaking her head, and Sartorius leans, kissing her on the cheek in a dramatic fashion.

Harry settles in one of the leather chairs Frank had brought into the library yesterday morning, his copy of James and the Giant Peach in his lap. It's a funny book, thus far, and Harry's going to mention how much he's enjoying it when he next writes Mr and Mrs Granger; he reads in silence for the next hour or so, occasionally glancing at Hayworth to see what she's doing. She mostly seems to be making careful sketches of the room, from a bird's eye position, and then he realizes that she's trying to map where the room adjoins the castle.

Harry is just leaning forwards in his seat to see how it fits in with Hayworth's existing map of the Slytherin common room and the dungeons when there's a tap on the ceiling above them. Harry looks up, staring at the black glass, but then there's a shift in one of the panels.

Blackness seems to steam away from glass above them, and Harry stares up, wide-eyed, as half of the panel disappears, but water doesn't stream into the room from the lake. A pale hand streaks over the glass, and Lindon Sartorius leans in, giving Hayworth an obnoxious wave from outside.

"Did he swim down here from the surface?" Harry asks, watching in horrified fascination as Sartorius holds up his wand, pulling away the layers of soil and muck clinging to the library's glass ceiling, and Hayworth nods her head.

"It's not as if I wanted to do it," she points out, and she looks up at Sartorius as he walks. He's the sort of person who scowls when he concentrates, and it seems he's concentrating hard, drawing his wand over the glass and dislodging the soil clinging to it. It rises in thick clumps into the lake water, and Sartorius pauses to Vanish it every few minutes.

A bubble is formed thickly around his head, letting him breath under the water, but he's stripped off his outer robe entirely, and his grey underpiece clings wetly to him in the water, its skirt floating around him. He doesn't seem to be put off at all by the cold of the lake, despite it being mid-December, and he works for maybe two hours, meticulously dragging every piece of soil away from the library's ceiling.

With green-tinged light filtering in from the lake above, the library looks more open, and Harry can't understand how he'd thought the ceiling was originally just black glass: the ceiling is like that of a conservatory, and it leaves the room feeling airy and bright despite being so far under the lake's surface.

It's beautiful, Harry thinks, watching sunlight shimmer on the floor, wavy and odd after passing through the water above them. Far more beautiful than he'd ever have expected.