Harry spent the better part of the next day in the mansion's study, pacing restlessly between towering bookshelves. The scent of parchment and old leather mingled with the fresh ink scrawled across the diagrams he'd drawn by hand.
Thalia deserved a weapon worthy of her heritage—a weapon that wouldn't splinter in a monster's jaws or break under the strain of her power. And he'd nearly resigned himself to enchanting an existing celestial bronze blade.
But the idea had come to him in the quiet hours before dawn, sparked by a memory:
Sitting on the velvet sofa with Dudley, a bowl of popcorn balanced precariously between them, the glowing blue of the TV screen illuminating their tired faces.
"That's the best bit," Dudley had whispered, practically vibrating. "Wait—just watch this bit—"
And a shimmering blade of blue light ignited in a Jedi's hand, humming with contained energy as it clashed against another, sparks flying.
Even after all this time, Harry hadn't forgotten how alive Dudley had looked watching those movies.
Why can't I make something like that?
But not plasma. Not technology. Something more fitting for Thalia—something born of her own power.
Lightning.
Contained, focused, deadly.
The idea was absurd, and he knew it.
But Harry Potter had spent his entire life doing absurd things.
That evening, while Thalia and Callie practiced forms in the garden, Harry approached them with his arms folded.
"I've been thinking about your sword," he began, trying to sound casual.
Thalia paused mid-swing, eyeing him suspiciously. "Oh? And what ridiculous scheme did you come up with this time?"
Callie propped her spear against her shoulder. "If it involves more monster transfigurations, I'm going back to bed."
Harry ignored her and looked straight at Thalia. "What if… instead of a regular blade, you had a weapon that could channel your lightning? Not just conduct it—contain it."
Thalia's brows drew together. "Like… a metal rod?"
"No." He took a slow breath. "Like a lightsaber."
Callie burst out laughing. "You've been watching too many movies."
Thalia, though, tilted her head, intrigued despite herself. "How would that even work?"
"I'm not exactly sure yet," Harry admitted, rubbing the back of his neck. "But I have a few theories. It wouldn't use plasma. The blade would be made of your own lightning—stabilized inside a containment field so it behaves like a sword. When you strike something, the energy would discharge."
Callie blinked. "That… actually sounds amazing."
"It's madness," Thalia said, though she couldn't quite keep the excitement out of her voice. "But… gods, I want to see it."
Harry grinned. "Good. Because if I'm going to attempt this, I need your help."
Thalia's eyebrows shot up. "My help?"
"You're the daughter of Zeus," Harry said simply. "If I'm going to anchor lightning into a magical housing, it has to be your lightning. Your essence. Otherwise it won't be stable."
She looked down at her calloused hands. "You think I can do that?"
"I think," Harry said quietly, "that if anyone can, it's you."
A small, fierce smile tugged at her mouth. "Alright then. When do we start?"
Harry glanced at Callie, who was staring at them in open awe. "Tomorrow morning. And you—" He looked at Callie. "—are going to help me with containment runes."
"Me?" she squeaked. "I'm not a wizard!"
"But you are excellent at focusing energy. That spear of yours—" He gestured at the enchanted weapon resting against the oak. "—is basically an energy conduit. You'll help me test the output."
Callie looked torn between terror and delight. "Fine. But if I die, I'm haunting you."
"Fair enough," Harry said, trying not to laugh.
That night, he stayed up late in the study, parchment scattered across every surface. He referenced everything—Magical Metallurgy, Runic Theory of Containment, even the Star Wars companion guide Dudley had insisted he keep "for research."
By moonlight, he etched his first prototype containment diagram, the runes looping and spiraling around a central point. At the center, he marked the sigil that would bind the lightning to Thalia's will.
Hermione appeared in the doorway around midnight, hair down and face weary. She watched him for a long time without speaking.
"You're really doing this," she said at last.
Harry looked up, ink smudged on his fingers. "Someone once told me it's good to have impossible goals."
Hermione walked over, studying the diagram. "You're insane."
"I know."
She reached out, squeezed his shoulder, and smiled faintly. "But you're exactly the kind of insane we need."
The next morning, Thalia stood barefoot in the clearing behind the mansion, her hands crackling with nervous energy. The air shimmered with heat and the faint scent of ozone.
Harry held the prototype hilt in both hands—no blade yet, just the carved obsidian cylinder etched with delicate runes.
"Ready?" he called.
Thalia flexed her fingers. "Born ready."
"Focus," Harry said gently. "Draw it from your core. Imagine the blade taking shape."
Lightning began to dance across her palms, coiling up her arms like living threads of silver. She grit her teeth, holding the energy steady as Harry lifted the hilt toward her.
"Channel it now."
A crack of thunder split the air as the lightning leapt from her hands into the runes. The containment sigils ignited, blazing white, and the hilt vibrated so violently Harry dropped it.
Creating a magical sword was never going to be easy. But creating a lightning sword—especially one that wouldn't burn Thalia and her allies alive the first time she swung it—turned out to be something closer to madness.
The second attempt lasted exactly nine seconds.
In the clearing behind the mansion, Harry knelt over a polished steel hilt, its surface etched with containment runes that shimmered under the morning sun. Thalia stood beside him, flexing her fingers nervously.
"All right," Harry said, voice tight with focus. "Channel slowly this time. Just enough to light the runes."
Thalia nodded, exhaling. "Here goes."
She raised her hands, and silver lightning leapt from her palms to the hilt. For a moment, it worked—pure blue energy began to form the suggestion of a blade. But almost immediately, sparks sprayed from the seams, the metal warping under the force.
"Harry—"
"Keep going!" he called, pushing magic into the stabilizing glyphs.
But the hilt vibrated violently in place. A whine built in the air, so high-pitched it felt like it was burrowing into Harry's skull.
With a deafening crack, the entire thing exploded in a shower of sparks and twisted shrapnel.
Thalia staggered back, shielding her face. "Well," she gasped, coughing smoke, "that was impressive."
Callie, watching from a safe distance, applauded half-heartedly. "At least it looked pretty."
The third attempt was no better.
Harry spent the entire afternoon engraving new amplification runes around the containment sigils, hoping to channel the lightning into an orderly current. This time, the blade actually formed to full length—a shimmering, three-foot arc of blue power—but Thalia's arms were shaking almost instantly.
"It's draining you," Harry realized as she struggled to hold it steady. "Drop it!"
The lightning flickered out. Thalia dropped to her knees, breath coming fast. "It's…too much," she panted. "I can't keep it going."
By the forth prototype, Harry was nearly out of ideas—and out of tools. The hilt snapped in half from internal heat after the first surge of lightning. Even he had to admit defeat was looming.
He spent that night in the study, head in his hands, frustration gnawing at the edges of his mind. The parchment around him was covered in frantic calculations, rune sequences, and half-scorched notes.
Hermione entered quietly, setting a plate of toast and a fresh cup of tea at his elbow. "You have to sleep sometime, you know."
"I will," he muttered, voice hoarse. "After I figure this out."
She looked at him with quiet understanding. "I already submitted your college applications," she said softly. "Someone has to keep your life together while you reinvent weapons technology."
He finally looked up and managed a tired smile. "Thanks."
"You're welcome." She hesitated, then added, "You'll get it right, Harry. You always do."
After the forth failure, Harry realized he couldn't do this with ordinary steel. The metal simply couldn't contain that much raw lightning without either melting or shattering.
Which meant he needed help.
The next morning, he paid a visit to Gringotts.
The goblin at the front desk raised an eyebrow as he approached. "Mr. Potter. What can we do for you today?"
"I need something," Harry said carefully, "stronger than anything I can buy in Doce Encanto. A hilt that can channel and withstand continuous lightning discharge."
"You understand," the goblin said, steepling long fingers, "that enchanted alloys of this grade are not made lightly. They are custom, and they are expensive."
Harry reached into the enchanted pouch at his hip and pulled out an ancient-looking ledger. "I have vaults. Family metals. I'm prepared to pay whatever it takes."
The goblin's eyes glittered. "Follow me."
Two days later, a small black coffer was delivered to the mansion, sealed with goblin runes.
Harry opened it on the library table, the others peering in curiously. Inside lay a hilt forged from a metal so dark it almost drank the light around it. When his fingers brushed it, a shiver ran up his arm—like the hum of contained power.
"What is it?" Callie breathed.
"Mithril alloy," Harry murmured. "With goblin-tempered runes. It can survive a dragon's breath and a thousand lightning strike."
Thalia looked at him, her eyes wide. "This is for me?"
He nodded. "Let's hope this time it holds."
The next attempt was different.
They waited until twilight, when the shadows pooled blue across the grass. Harry laid the hilt on a stone plinth, every rune carefully etched in fine lines along its length. He had spent hours refining them, adding amplification sequences so the blade would only draw a fraction of Thalia's power before multiplying it internally.
"Ready?" he asked softly.
Thalia stood at his side, her hands steady. "Ready."
He nodded. "Channel, slowly."
She raised her hands, palms open. This time, the lightning didn't roar from her fingers—it trickled in delicate threads, spiraling into the sigils like water soaking into dry soil. The runes came alive, glowing a deep sapphire.
Harry swallowed, his heart hammering. "More."
She gave a little more, and the containment glyphs brightened further—until a soft, resonant hum filled the clearing.
And then, with a single bright flare, the lightning formed a blade.
It was perfect.
Three feet long, a shimmering arc of controlled energy, pulsing like a living thing. Not a crackling whip, not a bolt of chaos—a sword.
Harry stepped back, wiping sweat from his brow. "Try lifting it."
Thalia reached out. For a terrifying second, he thought it would overload again. But her hand closed around the hilt—and the blade stabilized. The amplification runes glowed, sustaining the energy effortlessly.
Her eyes went wide. "It's…light. Like nothing."
Harry exhaled shakily. "That's because it's not a solid blade. It's your power, anchored. The runes will keep the drain to a trickle."
Carefully, she swung the sword. The blade hissed through the air, leaving a faint ozone trail.
"Oh gods," she whispered. "It actually worked."
Callie stepped forward, speechless. Hermione clapped a hand over her mouth, astonished.
Harry smiled, bone-deep relief flooding through him. "Congratulations, Thalia."
She looked at him, her expression fierce and proud. "Thank you."
Thalia had never looked so elated as when she first lifted the completed blade, the contained lightning humming like a living thing in her hands. She swung it once, testing the balance, and her grin was so wide Harry thought her face might crack.
But he raised his hand before she could start carving shapes into the air.
"Hold on," he said firmly. "It's not finished."
Thalia blinked. "What do you mean? It's perfect."
"It's powerful," Harry corrected, gesturing for her to power it down. "But it still needs containment and safety enchantments. Right now, if you touch anything metal with the side of the blade, it could arc straight through the hilt and burn you alive."
Callie made a strangled noise behind them. "Comforting."
"Which is why," Harry continued patiently, "I'm going to reinforce the runes and add a directional containment ward. That way, the lightning won't discharge into your hand or surroundings."
Thalia's shoulders sagged a little. "How long will that take?"
"A few days," Harry said. "And there's one more thing."
She arched an eyebrow. "Which is?"
"I want it to be something you can carry anywhere," Harry said. "A sword you can keep hidden until you need it."
Hermione, who had been watching from the porch, tilted her head. "Like a summoning charm?"
"Better," Harry said, already turning the hilt in his hands as he calculated the modifications. "I'm going to shrink it into a pendant."
Thalia blinked. "A what?"
"A pendant," he repeated. "When you wear it, it will look like an ordinary locket on a chain. But when you pull the miniature hilt free and channel power into it, it will revert to its true size and activate."
Callie clapped a hand over her mouth. "That's the coolest thing I've ever heard."
Thalia was quiet for a moment, eyes wide. "You can really do that?"
Harry smiled faintly. "I've done stranger things."
It took him the better part of a week.
Days passed in a blur of rune-carving, incantations, and precise Transfiguration. He tested every contingency—striking iron, steel, even a shield charmed to absorb kinetic energy. The blade held steady each time, the power focused to the same controlled length.
Hermione brought him meals he forgot to eat. Teddy toddled in to watch, eyes huge, before Andromeda shooed him back out again.
Finally, when every line of the containment runes glowed with a perfect, steady light, Harry set the hilt on the oak worktable and took a long breath.
Almost done.
He placed the locket casing beside it—a small, simple silver pendant etched with faint protective glyphs—and whispered the final incantation. Magic rippled over the worktable like water over glass. The hilt shimmered, shrank, and clicked neatly into the locket.
When it was finished, Harry actually sat back in the chair, exhausted and awed.
Even he could hardly believe what he had made.
That evening, he called Thalia into the study.
She entered cautiously, Callie trailing behind her. When she spotted the pendant lying on the velvet cloth, she froze.
"That's it?" she whispered.
Harry nodded, picking it up carefully by the chain. "Here."
She extended her hand, and he lowered the pendant into her palm. It looked so small and harmless—a pretty silver locket that could have held a photograph.
But they all knew better.
"It's all done?" she asked, voice hushed.
"Yes," Harry said. "The containment runes have been reinforced. The directional warding is stable. The amplification glyphs are calibrated so it won't drain you unless you sustain the blade for too long. And—" he tapped the pendant gently, "—if you pull this free and channel your power into it, it will expand and activate."
Thalia looked up at him, something fierce and vulnerable in her eyes. "Can I…?"
"Try it," Harry said softly.
She closed her fingers around the pendant and drew a slow breath. Then, with a flick of her wrist, she pulled the miniature hilt free.
A soft, resonant hum filled the room.
Lightning sparked across the carved metal, crackling with restrained energy. And then, with a bright blue flare, the blade ignited—three feet of shimmering, concentrated power that glowed in the dimness like a second sun.
Callie let out a gasp. Hermione actually clapped.
Thalia stared at the blade, awe and disbelief mingling in her expression. "It's perfect," she breathed.
Harry swallowed, feeling both proud and terrified. "Just remember," he said firmly, "this is not a toy. You're not to use it unless you're facing a monster, or if your life is in danger. Understand?"
She nodded immediately. "I swear."
"No sparring," he added, giving her a pointed look.
"I swear," Thalia said again, though she was grinning from ear to ear.
Harry relaxed, just a little. "Then it's yours."
She turned the blade in her hand, watching the lightning dance along its length. "Thank you," she said softly. "For everything."
He smiled. "Just promise me you'll stay alive to use it."
"I will," she said, and he believed her.
As the blade dimmed back into the hilt and she clipped the locket around her neck, Harry finally let himself exhale.
For the first time in weeks, he felt like he could rest.
But even as he watched Thalia and Callie leave the study—laughing, still awed by what he'd made—he knew this was only the beginning.
Because sooner or later, the monsters would come again.
And this time, they'd be ready.