Harry Potter: The Lion of the Serpent House

"Wow, you're really invisible!" Ron exclaimed.

"Ron, don't talk or run—it makes noise. The Invisibility Cloak doesn't hide sound. It's in Ten Truly Useful Magical Tools," Hermione scolded.

"How do you remember all that?" Ron asked, amazed.

After the Christmas party, Harry retrieved the Invisibility Cloak from the Slytherin dorm. He, Ron, and Hermione huddled beneath it to explore Hogwarts. The cloak was long enough to cover all three, though Hermione disliked squeezing close to Ron. Harry, flustered, wedged between them as they headed for the dungeons.

"Merry Christmas, Myrtle. It's Hermione," she called, tapping the girls' bathroom wall with her wand. The bathroom, wrecked at Halloween, was magically restored—likely McGonagall's work, Harry thought, admiring the spellcraft.

A gurgling sound preceded a silvery girl emerging from a toilet with a rush of water. Ron averted his eyes, but Hermione faced Myrtle calmly.

"Yes, we need to ask you something important," Hermione said.

"Myrtle, were you using Sonorus in here on Halloween night?" Harry asked, recalling a loud voice echoing from the bathroom. The troll likely followed it. If Myrtle was responsible, it was an unlucky coincidence; otherwise, someone deliberately lured the troll.

"No," Myrtle replied. "I'd love more outcast friends, but not if they're bullied more."

"Then it's either a Slytherin girl's prank or someone with malicious intent cast magic here," Harry concluded.

"That's too cruel for a prank!" Ron said, ignoring his brothers' antics.

"It's normal in Slytherin," Harry lied. Slytherins rarely targeted their own unless provoked. Hermione had mentioned Slytherin girls harassing her post-Halloween, and given their views on Muggle-borns, such malice wasn't impossible, even within the house.

"No, Harry, not this time," Hermione said firmly. "I know someone capable, but she couldn't manage magic that advanced. Hogwarts' structure has powerful protective charms—only an adult wizard could interfere."

"How do you know that?" Ron asked.

"Hermione memorized Hogwarts: A History," Ron answered, making her blush faintly.

"You've got good friends," Myrtle said, her tone joyful yet tinged with envy. Harry understood her feelings.

"An adult then? A seventh-year or older?" Harry suggested.

"Miss Myrtle, any clues? Anyone passing by the bathroom that night?" he asked politely.

Myrtle looked sad. "I'm sorry, I don't know. I wasn't here until that girl called me."

"It's okay. Knowing someone cast it intentionally helps. Thank you, Myrtle," Harry said.

"You're so kind, even to me. Such a pity you're in Slytherin," she replied.

"Slytherin's great," Harry defended.

"Not for me. I'm an outcast everywhere, especially there," Myrtle said, smiling briefly before returning to her sorrowful expression. Harry, watching her, thought she seemed alive. Despite Zabini's claims that ghosts lacked souls, Myrtle's emotions made Harry question the difference between them.

They left without a solid lead.

"Dead end again," Ron groaned. "Thought we'd find something."

"Don't lose heart, Harry," Hermione encouraged.

Harry nodded. They'd learned the attacker could bypass Hogwarts' wards, likely using Curse-level magic, linking the troll and Bludger incidents to the same culprit.

"Maybe catching Peter was a fluke," Harry muttered, feeling defeated. "Just a stack of lucky breaks."

An idea struck him: release a bought snake to spy and report suspicious people in Parseltongue. But Hogwarts was too vast, and a snake roaming corridors would be caught instantly. Only some Hufflepuffs strictly followed the no-magic-in-halls rule. Harry had seen Slytherins snitch to Filch, getting other houses punished, so often he'd grown numb to it.

"The first day…" Hermione began.

"What's up?" Harry asked.

"On the first day, Dumbledore warned us to avoid the fourth floor unless we wanted to die," she recalled.

Ron hesitated. "My brothers probably checked it already. Just Dumbledore's scare tactic—nothing there."

"No, we investigate every lead," Harry insisted, overriding Ron.

They climbed Hogwarts' shifting staircases toward the forbidden fourth floor. At a classroom door, they found it locked. Harry's palms sweated. A locked door meant something forbidden lay beyond. Maybe Dumbledore's warning was serious. He glanced at Ron and Hermione, who nodded beneath the cloak.

Together, then.

Recalling the troll fight, Harry steeled himself. "Alohomora."

A click sounded, and the door creaked open mournfully, admitting them to a dim room. Harry grimaced.

"I'll do it. Lumos!" Hermione lit her wand, illuminating the room through the cloak's gap. Her light revealed a door at the far end, guarded by a monstrous creature.

Harry wished it didn't exist. It resembled a massive, reddish-black dog with razor-sharp fangs capable of piercing steel, larger than the troll. Most terrifyingly, it had three heads. One began opening its eyes, reacting to the light.

"Run!" Ron yelled, grabbing Hermione.

As they reached the door, a metallic crash echoed behind them. They slammed it shut against the beast's roars, soaked in cold sweat, Harry's glasses fogged.

"Cerberus!" Ron stammered, trembling.

"Why's that thing in a school?" Harry agreed, horrified. What if a student wandered in? Were warnings and locks enough to absolve responsibility for deaths?

Hermione, after deep breaths, regained composure. "Did you notice? That dog was guarding a door. There's something beyond it!"

"Why guard it here? Why not a bank?" Ron snapped.

"Maybe they don't have an account," Harry mused, recalling Hagrid's comment about the difficulty of opening a wizarding bank account. Ron scoffed.

"Maybe the troll's culprit was after whatever's there," Harry suggested.

"That's our lead. They caused the toilet distraction to slip through," Hermione agreed.

"Snape's looking suspicious again. Maybe the Cerberus bit him at Halloween," Ron said.

"I don't want it to be a Slytherin teacher…" Harry admitted. Though he didn't fully suspect Snape, considering him a potential villain was the painful part of their search.

Exhausted, they shed the cloak and collapsed. They continued exploring under the Invisibility Cloak, evading Mrs. Norris, as Hermione disliked smart animals prowling. Harry had never explored Hogwarts so thoroughly, and with Ron and Hermione, it was thrilling.

When Hermione's fatigue showed, they stumbled upon a large mirror in an empty classroom.