"Are we... are we really going in, D-Dog?"
Ron's knuckles were white, clutching his wand tightly as he stared at the dark, empty corridor ahead. Under Dudley's lead, they had come to the place they'd avoided during their previous night-time escapades: the forbidden corridor on the fourth floor. Ron's nervousness was contagious, affecting Harry and Malfoy, who were also feeling the tension. Dumbledore's warning from the start-of-term feast still echoed in their ears: "Those who do not wish to suffer a most painful death must not go down the right-hand corridor."
"Of course," Dudley replied. "This is a test from Professor Dumbledore."
Dudley then pulled a few amulets from his pocket and handed them to the others, telling them to put them on.
"What are these?" they asked, confused.
"They're good luck charms," he said, and with that, Dudley led the way, stepping into the darkness. The others exchanged a puzzled glance but put on the amulets and quickly followed.
At the end of the corridor was a locked door. Without even bothering to put his hands together, Dudley simply grabbed the lock and with a powerful tug, the seemingly sturdy iron lock snapped into two pieces.
"Alohomora (the Muggle way)."
With a creak, the door swung open, revealing a gigantic three-headed dog.
"A three-headed dog!"
It was the very same beast that had bitten Snape. Now, the dog's six huge, yellow eyes stared down at the students. Harry and the others froze in terror, rooted to the spot. They were so close they could feel the foul, hot breath coming from the three massive mouths. As young wizards new to the magical world, they had never seen anything like this. They were petrified, as if a Freezing Charm had been cast on them. A creature that could injure Snape was certainly not something a group of first-years could hope to face. Fortunately, a thick chain was looped around the dog's neck, preventing it from leaving the room or attacking them.
"Get past it, quickly! Leave this to me."
Dudley's voice was a shot of courage, an invisible charm that bolstered their spirits. He pulled an iron ingot from his pouch, clapped his hands together, and the ingot transformed into countless iron chains that wrapped around the dog's four legs, binding it from all sides. Harry and the others seized the chance, opening the trapdoor next to the beast and jumping through, one after another.
Before she went down, Hermione shot a worried glance at Dudley. Seeing him offer a calm, reassuring smile, she took the plunge.
Once he was sure they were all gone, Dudley released the chains binding the three-headed dog. As soon as it was free, the beast lunged at him. Its job was to guard the room and keep everyone out. Several people had already entered, but at the very least, this one couldn't be allowed to get through.
In the next moment, all three of the dog's heads froze in shock. Dudley, who had been a regular height, suddenly seemed to inflate like a balloon, growing to an astonishing seven and a half feet tall. He walked over to the three-headed dog, and as two of the heads lunged to bite him, he grabbed one head in each hand and slammed them together.
"You like biting, do you?"
Thump.
"How about that for a bite?"
Another thump.
Thump.
"Want to try another one?"
One more thump.
Thump.
A series of dull thuds echoed through the room. When Dudley let go, the two heads flopped to the ground. Stars seemed to swirl around their heads, their eyes were crossed, their tongues lolled out, and they looked completely dazed and broken.
The familiar sensation and terrifying strength made the middle head, the one that hadn't been attacked, remember its owner, Hagrid. Hagrid used to play with them in the same rough way, and it was a truly traumatizing memory. This move from Dudley completely subdued the three-headed dog. The one conscious head didn't dare to attack and simply stared at Dudley with wariness in its eyes. It might be a big dog, but it wasn't a stupid one. It knew when it was outmatched.
As Dudley stepped forward, the dog took a step back. Another step from Dudley, another step back from the dog... until it was pressed against the wall.
Dudley took one more step.
There was nowhere left to retreat.
This final step seemed to trigger something in the three-headed dog. With a mournful whine—"Awooo!"—it closed its eyes and started thrashing its limbs wildly in the air, flailing about on the spot.
Did the three-headed dog just use Fury Swipes? Or was that a Splash attack?
Dudley had no idea what had caused this sudden, frantic fit. He eyed the dog suspiciously. He could understand magical creatures, but not this mindless yelping. He opened the trapdoor without hesitation and jumped down. He really hadn't intended to hit the dog again, but its strange behavior made him wonder if it had rabies. He could only hope Snape was alright, especially since he'd been bitten on the leg and the wound had gone straight through.
After Dudley had been gone for a while, the three-headed dog, with its eyes still closed, sniffed the air. When Dudley's scent became fainter and fainter, it slowly opened one eye, cautiously peering around.
He's gone?
Confirming that Dudley was truly gone, it opened both eyes and let out a very human-like sigh of relief. It was absolutely certain that the person had power similar to its owner. If it had fought, it definitely would've gotten a beating. The most crucial detail was that it had smelled a hint of rock cake on the boy. Yes, it was definitely Hagrid's rock cakes. Maybe it was better to just play dumb. They called it a stupid dog, but it wasn't stupid at all; sometimes, it was quite clever.
But before it could wake up its two knocked-out heads, it smelled the scent of another stranger.
'Whoever it is, I'll get you this time!'
The three-headed dog bared its sharp teeth. However, after waiting for a while, no one appeared. Instead, the sound of a beautiful harp began to float into the room.
Before long, a harp with two legs hopped and skipped inside. The one remaining head of the three-headed dog seemed to be under a Hypnotic Charm. It slowly, slowly... sank to the floor, its eyelids getting heavier and heavier... and then a loud snoring sound filled the room.
At that moment, a man with a turban on his head peeked half a head around the door frame, trying to see what was inside. After confirming that the three-headed dog was asleep, he relaxed and went from tiptoeing to taking big steps. The fact that the three-headed dog could be lulled to sleep by music was a secret he'd paid a heavy price to get from that big oaf, Hagrid—a dragon egg.
Unfortunately, the man with the turban didn't know that while a three-headed dog can be hypnotized by music, that's not necessarily true for one suffering from a mild concussion. As he was about to open the trapdoor, the two heads that had been knocked out suddenly awoke. With one eye looking up and the other looking down, their necks crooked and drooling, they approached him and opened their mouths wide, aiming for his backside.