Quirell's POV
Let's rewind a few hours before Harry and the others attempted to infiltrate.
I, Quirinus Quirrell, had been preparing to steal the Philosopher's Stone for the Dark Lord Voldemort. I had items to avoid curses and antidotes hidden in my pocket. Dumbledore, that old fool, should be heading to the Ministry of Magic by now. There's no chance but today. Besides, this body, tainted by unicorn blood, was reaching its limit.
I opened the first door and entered. Cerberus noticed me and emitted a fierce aura. I quickly activated the harp that plays itself, based on the information I got from that foolish Keeper of the Grounds. He should fall asleep in no time.
However, Cerberus charged toward me with unwavering speed and determination, with the intention of biting me. I managed to dodge, but it was an unexpected turn of events.
"Kill!"
A command echoed in my mind from behind.
"Avada Kedavra, perish!"
A burst of green light struck Cerberus directly. This curse ends all life. As I tried to move toward the next door, a powerful impact from behind sent me flying. I rolled on the floor and crashed into the wall. Thanks to my defensive items, I survived, but it seems I've broken several ribs. Cerberus was still alive.
"Kill! Kill! Kill!"
"Why won't you die?! My master, what should I..."
"Perhaps Dumbledore... used a Horcrux?! No, that's not it... Quirrell, use Fiendfyre!"
"Yes!"
While barely fending off Cerberus's fierce attacks, I aimed Fiendfyre at it. Cerberus was engulfed in flames and finally perished. Originally, the plan was to proceed unharmed without using any magic. What a failure.
I arrived in the next room. It was dark and damp. Devilish traps were planted everywhere.
"Damn it!"
I cursed and emitted light from my wand. However, unlike Cerberus, this time, it seemed the vines were trying to strangle me to death. While avoiding them and heading to the next room, I got entangled a few times. Each time, excruciating pain shot through me. When I finally reached the next room and examined the entangled parts, I saw that they had swollen significantly, with numerous thorn marks.
"What is this...? There shouldn't have been thorns or any traps like this..."
My consciousness began to blur. I couldn't make out anything anymore.
"Drink the antidote! You fool, it's poison!"
Following the voice from behind, I quickly drank the potion from my pocket.
"I... what have I...?"
I managed to recover somehow, though it's unclear which antidote was effective. My body still felt sluggish, but I could move.
Looking around, winged keys were flying all around. There was a broomstick in the center, most likely used to catch the correct key.
"Be cautious. When you grab the correct key, the others will likely attack," I warned myself.
Thanks to my master, I quickly found the right key. As expected, the keys immediately attacked. However, something unexpected happened.
"Arrgh! My arm!"
Intense pain surged through the arm that held the key. I couldn't let go, so I had to endure it. The door opened, but the key wouldn't release from my hand.
"My master, what should I do?!"
"Sever it! Right now!"
"But..."
"If you don't cut it, you'll die!"
I severed my left arm above the elbow. Without even stopping the bleeding, I rolled into the next room.
Struggling to my feet, I was immediately attacked by giant chess pieces. I fled while trying to stop the bleeding. I used up all the healing potions and unicorn blood I had brought to make myself functional again.
"Confringo, explode! Confringo, explode! Confringo, explode!"
I blasted the chess pieces, but in the next moment, they reverted back to their original state, like a Muggle's video recorder in reverse.
"Target the king! That's the core!"
I followed the command and aimed for the king, but other pieces blocked my way. I continued to use magic while retreating. My senses gradually became distorted as I hadn't completely removed the toxins and curses from earlier.
"Bombarda Maxima, shatter completely!"
After more than thirty minutes, I finally shattered the king. I couldn't go on... I was going to die...
"Don't rest! We don't know when that old fool will return! Move forward!"
Driven by fear of my master, I pressed on, with my mental state deteriorating. Yes... the next trap was my own creation... If it's a troll, there should be no problem...
But that hope was quickly shattered. There was indeed a troll inside, but it shouldn't have been wearing full-body armor. The armor rushed toward me. If it were a troll, I could control it. No matter how it was being controlled by magic or potions, there should be no issue. At least, that's what I thought... But it didn't obey my commands. The armored troll swung a massive sword at me. I had no ability left to dodge...
(Oh... I can't evade this... I'm going to die...)
But in the next moment, my body had evaded the sword. Not only that, it moved without my will being involved.
"Quirrel, I will use your body. As compensation, your soul will be gradually depleted, but that should be of no concern. It will serve as the foundation for the great Lord Voldemort's resurrection,"
My master said something. I didn't understand. All I felt was intense pain, suffering, and a sensation of fading away.
"Avada Kedavra! Still won't die, huh... This is a magic that animates a troll's corpse through the enchanted armor. I see, it won't obey Quirrel's commands. In that case!"
My master used magic far beyond my capabilities, focusing on the arm holding the sword, with results that cost me my existence. Dozens of spells hit me, my arm shattered, and the detached sword pinned the armor to the wall. At the same time, I regained control over my body.
"Indeed, controlling the body for an extended period requires more power... Quirrel, hurry!"
I followed the orders and moved on.
In a small room, there were several potions placed. As soon as I entered, black flames erupted from all sides. A challenge was presented. It seemed that to proceed, I needed to drink the correct potion.
"10... 9... 8..."
There was a time limit. The flames were gradually closing in, but I could no longer think about anything.
"A trivial puzzle like this... Don't underestimate me! The one on the far left! Drink it quickly and proceed!"
I drank it and moved forward, enduring the burning sensation throughout my entire body. Inside me, the potion was breaking me down.
"What did you say!? You...!"
I couldn't even scream as my body advanced on its own. As I collapsed beyond the flames, the last thing I saw was a child calmly observing me.
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Leo's POV
As planned, the intruder had perished by the time they reached the final room. The combination of devilish traps, poison, curses on the keys, poison potions, and the exhaustion and magical depletion from three battles had been calculated to ensure the demise of any wizard.
A black mist emanated from Quirrel's lifeless body, gradually taking the form of a snake-like face.
"Pleased to make your acquaintance, Lord Voldemort, the Dark Lord. I had various things I wanted to discuss with you, but... it seems we're out of time. Headmaster Dumbledore has arrived at Hogwarts. It would be wise to flee."
"It's regrettable, but I have no choice this time. What about you, Leonard Taylor? Will you let me go?"
"I haven't prepared to capture you in your current state, and my only orders are to protect the Philosopher's Stone. I hope we can have a proper conversation the next time we meet."
"Hmph. I'll consider it when I'm fully resurrected. I'm also interested in your 'eye'."
With that, the black mist passed through the wall and disappeared somewhere.
Standing in front of the Mirror of Erised, Leo realized that Dumbledore hadn't informed him about the final enchantment.
(Well, now that the Dark Lord has departed, I suppose it's time to analyze.)
As he began his analysis, Leo in the mirror placed the Philosopher's Stone in his pocket.
"Hmm? I see... So, it can't be obtained by those who want to use it, but it can be obtained by those who want to find it. I suppose it's fine for me because I wanted to study it, not use it."
For now, with Dumbledore's return, he decided to analyze the Philosopher's Stone while heading back.
(It seems Harry Potter is heading this way; we might run into each other.)
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Harry's POV
On the other side of the door stood none other than Leonard Taylor. He looked at us without so much as raising an eyebrow.
"Leonard Taylor! What are you doing here? Did you come after the Philosopher's Stone too? I see! You're one of Snape's allies!"
Ron and I drew our wands, But that guy is staring at the stone in his hand without looking at us. That guy was infuriating... a stone?
"I can't believe it... Is that stone?"
"Well, well, it is indeed. For now, put away your wands."
A voice of a great wizard came from behind. When I turned around, there was Professor Dumbledore standing there. This meant victory for us!
"Headmaster Dumbledore! You've returned! This guy and Snape were after the Philosopher's Stone!"
"Ah, Harry, it's a misunderstanding. Leo, how's the situation?"
"Yes. Professor Quirrell is dead. Voldemort fled upon learning of your return, Headmaster. We didn't have the preparations to capture his spirit, so he got away. After standing in front of the Mirror of Erised, I obtained the Philosopher's Stone, so I brought it here. What should we do?"
What? What is he saying? Why did Professor Quirrell die, and why is Voldemort's name being mentioned? What about Snape? Did Dumbledore know about all of this?
"Headmaster Dumbledore, what on earth is going on? Was Voldemort here? What about Snape?"
(That's right, indeed. Professor Quirrell was possessed by Voldemort, and he aimed for the Philosopher's Stone to achieve his resurrection. I asked Leonard here to reinforce its protection. Well, it's quite late now. Return to your dormitories so that Filch doesn't catch you. Leo, come with me to the headmaster's office.)
Ron and I returned to our common room without understanding anything. In the end, today had concluded without us doing anything.
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The headmaster's office.
"So, that's the situation. I will return the Philosopher's Stone."
"I see, you've done well. And you may keep the Philosopher's Stone. I obtained permission from Nicholas. During the summer break, visit the Nicholas couple. They'd like to have a discussion with you about the Philosopher's Stone before He depart. They are eager to talk about it."
"Thank you very much! May I return to the study room to analyze it right away?"
"Of course, you may. Voldemort is unlikely to target it anymore, but keep the Philosopher's Stone hidden. We can announce that we've destroyed the Philosopher's Stone tomorrow. You've done an excellent job defending it. Both Nicholas and I allowed your research because of your character. That's why we granted permission for the Philosopher's Stone."
"I see. Thank you very much!"
Without much listening to Dumbledore's words, Leo quickly left the headmaster's office.
In the headmaster's office, Dumbledore took a moment to rest.
(We've prevented the Philosopher's Stone from falling into Tom's hands. However, Leonard Taylor's power exceeded my expectations. Moreover, he has no aversion to the darkness. He seems to be pursuing magic purely for the sake of it. But precisely because of that, he may unhesitatingly delve into the darkness. Was it the right decision to hand over the Philosopher's Stone? I wanted Harry to confront Voldemort and follow the path of a hero, but Leonard's influence has kept him mostly detached from this incident. Now, what should I do next...)
The threat of darkness had passed, but Dumbledore's inner turmoil remained unabated.
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Now, the defense of the Philosopher's Stone is complete.
Here are the details of the traps:
Cerberus
The weakness to music has been overcome, and Cerberus has increased intelligence. Additionally, like a Horcrux, its soul is split, with each head acting as a pseudo-Horcrux. This renders most spells ineffective, including the Killing Curse. Voldemort quickly detected this because he was adept at using Horcruxes and used Fiendfyre to destroy it. Since the soul was only split within its body, it perished. Leo, who didn't know about Horcruxes, created this with his unique theory. Dumbledore's concern was focused on this.
Devil's Trap
The weakness of light has been overcome through selective breeding. The vines are armed with numerous poison needles. Although the effects can be temporarily countered with an antidote, it becomes too late as the poison lurks within the victim's body unnoticed.
Room of Keys
Overall, the speed of the keys has been increased. When the correct key is taken, a curse is activated, and it becomes impossible to let go, similar to the ring that Dumbledore got ensnared by in the original story. The only way to escape is to sever the connection, but the curse lingers in the body.
Wizard's Chess
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All chess pieces, both black and white, attack. You must destroy the core King or they will regenerate infinitely
Troll
Considering Quirrell, the corpse of a troll is utilized. The armor is designed similar to Granblue Fantasy's Colossus Magna. The armor is quite sturdy but not invincible.
Potion Logic Puzzle
The puzzle isn't overly difficult, but there's a 10-second time limit. However, all potions that appear are lethal poisons. Over time, you either burn to death or die from drinking the poison. The potions explosively enhance the effects of deadly poison, the Devil's Trap poison, and the curse from the Room of Keys.
Mirror of Erised
Since Leo wasn't involved, it remains the same as in the original story.
These are the improvements made to Leo's traps. They could have been made much more deadly, but it was adjusted so that they would die in the last room and experience all the traps' performances.
Harry and Ron finished without even stepping into a single room. They're the protagonists of the original story, after all...
Leo gets the Philosopher's Stone as a reward! In exchange, Dumbledore's anguish intensifies!
The Philosopher's Stone arc will conclude in the next chapter.