This is actually the second part I've posted, so if you haven't read Y1,P6, go and do so now.
I mean, it's not mandatory, but it'd be nice to get context for what exactly caused this mess.
Harry Potter was used to being in many strange situations.
All his life had been a series of coincidences, you see.
First, he had been lied to about his parents by his abusive Aunt and Uncle, then he had been not-quite-abducted by quite possibly the largest man he had ever seen; due to the fact that he was actually a wizard. Last year, he had accidentally killed his possessed professor, after having run a gauntlet involving a gigantic chess set, flying keys, and even a logic puzzle.
But nothing had quite prepared him for this.
Beside Harry, stood his steadfast friend Ronald Weasley, youngest male of the Weasley Family.
They had come down to the Chamber for a reason, of course.
Ginny Weasley, Ron's little sister, had disappeared, and there was another message on a wall, threatening her doom. Her dorm mate had been unable to confirm her location, as she had unfortunately had a run-in with the monster, and now lay paralysed in the medical wing.
The message, unlike the last two, was in a slightly… different… style than before.
Although it began threatening, it slowly devolved into a psychotic, nearly-incoherent rant, before further devolving into a two-hundred word eulogy on Merlin. When the two had left to meet the twins, Filch had been quietly discussing just flat out replacing the wall the message was written on with magic: an unheard of tactic which would have never seen the light of day otherwise.
It had taken begging to Fred and George to find Ginny's position: apparently the twins had acquired a magical map some time ago, and had been keeping track of Ginny over the last while. It had taken a little bit more effort, but Harry and Ron had managed to find the entrance, without giving anything away to the two.
Still, neither Harry nor Ron were willing to risk the life of Ginny, and had broken into the Chamber unassisted, both deeply hoping that what they were to encounter would be a prank, rather than any true danger. They both briefly considered waking Hermione, but knew that she would be busy studying for her tests.
Both boys hoped that what they were doing would not lead to a terrible mistake.
The Chamber of Secrets was dark, vast, and foreboding. The sound of scurrying vermin, dripping pipes, and the settling of stone echoed through the stale air. Countless stone pillars decorated the room, each entwined with stone snakes, each detailed down to the single scale.
It was also apparently home to a young man, who was on his back, screaming about creatures coming from the walls. The teen's eyes were nearly entirely red, with only a shade's difference between his bloodshot eyes and crimson irises.
Harry had noticed just earlier that the teen in front of them was not entirely solid: reaching out to the fallen boy merely led to the proffered hand passing through. The sight of this caused both Harry and Ron's hearts to drop a little. Neither considered the idea of having died and becoming a ghost in the Chamber a punishment unlike hell itself. To imagine this poor ghost suffering all of these years, alone and isolated...
They were about to proceed further into the Chamber, when the ghost finally shrieked an intelligible sentence. "THEY'RE EVERYWHERE! SLYTHERIN'S MONSTER, KILL THEM ALL!".
After a moment of silence, the deafening grinding of stone filled the air, before a snake the width of a bus slowly meandered past the two Gryffindors, headed directly for the entrance.
The two students looked at each other, before coming to a startling conclusion: if the snake was not stopped now, it could potentially kill everyone in the school!
Together, they did their best to draw the attention of the sixty-foot-long beast, first by way of haphazard Parseltongue, and then by mere hurled insults.
It was only due to the timely intervention of a renegade phoenix, and its magical cargo, were the duo able to slay the beast, its massive maw now divorced from its scaled body. Harry's body still shivered from the aftereffects of the beast's poison, even after it had been neutralised by the tears of the phoenix.
Now both out of breath, Harry and Ron continued past where the ghost had been, which was now occupied by the corpse of the giant snake. The ghost was of course still wailing, but its new position did more than enough to muffle it completely.
Hesitantly, they approached the final gate. As they both took a deep breath, they nodded to one another: no matter what was on the other side, they would save Ginny, or die trying.
With a flourishing motion, they threw the doors aside, before charging into the room ahead.
What they saw in the center chamber brought bile to their throats, and curses to their lips.
In front of them, was absolute, pure, indisputable evil.
A book sat on the ground, as wisps of energy slowly rose from the body of Ginevra Weasley, before shooting towards the book. Bit by bit, it was draining the soul of its victim, its foul presence pervading the very air, essence and mind of the innocent it had attached itself to.
"That's... just not right. It's just not right!" screamed Ron, his eyes threatening to escape the confines of his skull.
The book itself was a garish pink, and sparkled in the dim light. Every surface of the book was coated in glitter.
On the front cover, a massive, hot-pink pink heart took center stage, adorned only with the words "T. M. Riddle's Super Ultra Mega Special Diary", written in black sharpie. Slightly below that, was another line of text in flowing cursive, in a brilliant purple: "A gift from Mommy".
Shaking in horror, Ron barely managed to choke out "It's evil, Harry. We have to destroy it. For the good of the world."
Resolve filled Harry's body, as he drew his now-bloody sword to its full height. He approached the abomination against good taste with the determination of an executioner.
The poor book did not deserve to exist like this. No book did. Whatever foul thing had been done to it had rendered it unsavable. He could only destroy it, to save the shame of its owner.
The first slash rent a gouge in the diary. But the book would not die: from its gaping wound, spewed more glitter, a revolting mixture of pink, purple, and lime green. It soaked into the floor, leaving a spot which would stain the tiles of the chamber forever.
Each additional slash only gave a rise in pitch to Ron's shrieking, until it had exceeded all expectations of human range. "It's not working! IT'S NOT WORKING!" he wailed, as the horror continued to exist, against all attempts of the contrary.
However, the flow eventually stopped. Slowly, the bleeding of glitter ground to a halt.
Harry collapsed to a knee, now leaning on the sword, its blade sunk into the cobblestones below. As the sound of shallow breathing echoed through the chamber, both boys could hear a final muffled note of baleful wailing from the spectre, before it mercifully passed on, hopefully to join the afterlife, far away from this dank and isolated chamber.
Not willing to touch the accursed book with his bare hands, Harry once more impaled it, before holding it on the edge of his new sword, as far away from his body as he possibly could. It still occasionally dripped glitter and black ink, dotting the stones with an alternating black and shiny pattern.
It was at this point that Ginny woke up. She rose to her feet, and stretched, before blearily gazing about the chamber, unsure of why she had woken up where she had.
Not like Harry or Ron noticed: They were too busy shaking in fear and horror at what they had just witnessed.
Ginny spent a short while attempting to draw the attention of her traumatised knight in shining armor, before finally turning away in a huff until they were ready to escort her out.
Miles away, the shade of Voldemort felt at once both a massive surge of relief, shame, and anguish.
It did not like those feelings.