(revised, correction of minor typing/punctuation errors, 20th April, 2014)
Disclaimer: I am not J. K. Rowling. I do not own Harry Potter.
Note: The following originated as an idea during ongoing development of one of my long-term writing projects. Whilst I concluded that it wouldn't, ultimately, fit in what I was writing at the time (the slight silliness of tone was inappropriate), it took on a sort of life of its own and refused to go away. This one-shot is the result. To set the scene, this one-shot takes place as the 1992-1993 Hogwarts school year is winding down. Unlike in canon, 'The Heir' tended to target mostly Ravenclaws, and irrespective of blood-status. Although it came out that Harry Potter was a Parselmouth, he had some highly convincing alibis during some of the attacks. And unlike in canon, things do not conclude in this universe with Ginevra Weasley disappearing and a mad dash by Harry and his friends to try and discover and enter the Chamber of Secrets...
This story is rated 'T'.
Severus Snape wasn't sure what to make of the bewildering events of the past few hours – the unexpected culmination of the weeks of slow torture and suspicion building in the corridors of Hogwarts – but he had an uneasy feeling that something, somewhere, was fishy.
A Ravenclaw student, Marietta Edgecombe, and this year's excuse of a defence against the dark arts teacher, Gilderoy Lockhart, had been discovered to have apparently obliviated each other in some sort of fight or duel in the school trophy room. A search of Marietta's trunk in the Ravenclaw dormitories for any clues as to what might have precipitated this confrontation (carried out once Marietta and Lockhart had been removed to the infirmary), had turned up some distinctly disturbing evidence – including a map of the school, several books from the restricted section of the library containing very advanced magic (which Miss Edgecombe had no lawful reason to have in her trunk), and a personal diary full of increasingly deluded paranoid ramblings about her fellow Ravenclaws. Scribbled inside the front-cover of the diary had been a list of names, corresponding to those the diary writer apparently considered out to 'get' her, all too many of the names on which list were horribly familiar to the Hogwarts staff, for the worst of reasons. In fact there wasn't a single petrification victim of the past school year, whose name hadn't featured on the list in the diary – and worse still, every single petrification victim had been 'checked off' the list.
Reading between the lines, the obvious conclusion was that Marietta Edgecombe had been the 'Heir of Slytherin' and responsible for the terrors of the past school year.
Apparently either she'd suspected Lockhart was onto her, or Lockhart had developed suspicions about her and decided to try to do something heroic for once, and the two had fought – and now neither was in much of a state to answer any questions coherently.
And, a check of the school archives had rapidly determined that at least one of Miss Edgecombe's recent forebears had been a pupil at the school in the 1940's, when the Chamber of Secrets had been opened previously.
It seemed an obvious open-and-shut case, and yet… and yet something about the whole business bothered Severus Snape. Something was either out of place with the picture, or had yet to be spotted.
There came a knock at the door of his office, distracting him from his private ponderings of the situation.
He opened it and saw a blonde haired girl standing there, something clutched in one hand. She was someone Severus Snape was all too familiar with – the sort of student, whom even upon only a couple of minutes' acquaintance tended to emblazon themselves upon a teacher's memory, and upon any longer contact to rapidly become a feature of staffroom anecdotes and horror-stories for years afterwards.
"What is it that you want, Miss Lovegood?" Severus Snape asked her.
"You're a responsible teacher, aren't you?"
That was the sort of question all too typical of Miss Lovegood. She had a habit of saying or asking things that were socially irresponsible or tactless in the extreme – and frequently so on more than just the obvious level.
"All the Hogwarts teachers are supposed to be responsible, Miss Lovegood." Severus responded, whilst managing to restrain himself from commenting upon how there might be evidence to indicate certain notable exceptions. One didn't mouth off about one's fellow staff – not even Lockhart – to first years, except in extreme circumstances. "But to answer your question, yes, I consider myself a responsible member of this institution's teaching staff."
Luna Lovegood cocked her head on one side, looking him up and down, apparently considering his answer.
"Alright then." she said, thrusting the thing she had been clutching at him. It was a book of some sort – or at least the remains of one, with a prominent hole right through it. "This needs disposing of with extreme care by a responsible adult. You should be careful in handling it. Something even more dangerous and venomous than Marietta Edgecombe bit it for me."
Apparently news had spread fast, at least through Ravenclaw house, about Marietta's suspected activities – either that or Miss Lovegood had had some sort of dispute of her own with the older Ravenclaw.
"What is it, and how did you come upon it, Miss Lovegood?" Severus took the book from her, being careful how he handled it. "And has anyone coming into contact with it shown signs of any adverse effects?"
"Someone mysteriously slipped it to me, and it was something unbelievably dangerous – in that it was the diary of a teenage boy." Miss Lovegood said. "It was interesting for a while, but it got rather repetitive, angsty, and meglomaniacal in the end. So I shut it up. Permanently." She stopped and blinked and cocked her head again, seeming to think carefully. "Adverse effects? I don't think so. Not to anyone who's actually handled it. It was actually rather educational on some points, but not directly harmful." She shrugged. "After all, it was only the thoughts of a whiny, rather insecure, teenager."
Being careful of how he handled it Severus quickly flicked through the book, but it was difficult, with all the black stuff staining practically every page – which might be ink, or might be a toxic substance as Miss Lovegood had alluded to – to make out what it had ever had written in it.
"Thank-you, Miss Lovegood." Severus shut the book. "I shall take care to duly dispose of it. Is there anything else?"
"No. That's all. Well unless you want to buy a subscription to The Quibbler? I would like to offer you a year's free subscription, but that might be taken as an attempt to bribe a member of the teaching staff, which of course would be beneath the standards of as fine a publication as my father oversees."
"I do not require a subscription to The Quibbler at this point, Miss Lovegood." Severus said. "You may go then."
She turned and skipped away down the hallway, humming tunelessly as she went.
Over the summer which followed, Severus Snape kept an eye on The Quibbler, nonetheless, out of an inexplicable instinct, and was surprised to see a feature by 'our junior reporter at Hogwarts' under the title 'Interview with the Monster of Slytherin'. Actually, the article in question made it rather difficult for him to get hold of a copy of the July edition of The Quibbler, since officially the whole 'Chamber of Secrets' thing at Hogwarts was being treated as a hoax by the Ministry of Magic and Hogwarts board of governors, carried out by an insane and dangerous Ravenclaw prodigy with a grudge principally against members of her own house. As part of their attempts to make the whole thing 'go away', the Ministry was suppressing anything in print which mentioned the Chamber of Secrets, either directly or obliquely, including practically the entire print run of the July issue of The Quibbler.
The whole business was nonetheless, despite the ministry's efforts, much talked about (especially with Marietta and Lockhart both certifiably insane and removed to St. Mungo's, due to their having apparently obliviated one another quite so thoroughly)… at least until the next sensation came along, with Sirius Black's escape from Azkaban.
For those to some extent as in the dark as Severus Snape as to what has been going on, Luna Lovegood ended up with T. M. Riddle's diary, and proved less susceptible to its domination than its canon victim. She used it to assist her in getting her revenge on those who had been bullying her throughout the year (including setting Marietta up to take the fall), learnt Parseltongue from it*, and then disposed of it once it ceased to be useful/interesting. Harry Potter still had some things going on during the year (including Dobby's 'helpful' attempts to get him sent back to Surrey), but ended up completely uninvolved in the final wrap up. Luna Lovegood is the only pupil at Hogwarts aware of where the Chamber of Secrets is located or how to get into it, as of the end of this story.
I have no idea if Marietta Edgecombe is amongst Luna's tormentors in canon, but she is in this universe.
This story is a one-shot.
*Albus Dumbledore demonstrates in the book version of 'Half-Blood Prince' that it's possible for a wizard in canon to learn at least to understand Parseltongue, and Ron Weasley proves able to imitate the sounds to get into the Chamber of Secrets in the book version of 'Deathly Hallows'.