After dinner, Regulus headed into the library.
Madam Pince sat behind the desk at the entrance, polishing her glasses with a soft cloth. When she saw him, she only lifted her eyelids slightly and said nothing.
The library still wasn't very crowded. A few seventh-years were digging through references in a corner, two Ravenclaw girls leaned close together and whispered over notes, and a handful of Hufflepuffs were rushing to finish homework.
Regulus went to the Charms section and pulled out Common Spells and Their Variations.
The book was old, the cover worn pale along the edges. The pages had yellowed with age, but everything inside was clean, orderly, and free of bent corners.
He found a seat near a window, opened to where he'd left off, and started reading the analysis of the Knockback Jinx.
The spell itself was simple, he'd learned it ages ago, but other people's thinking could still be useful. The book described a combined use of the Knockback Jinx and a shielding charm that could send someone flying a great distance.
Outside the window, the sky darkened. One by one, the castle's lamps came alive.
Regulus turned a page, and his mind slid to something else.
Last term, he'd slipped into the Restricted Section more than once, wrapped head to toe in an improved Disillusionment Charm that blocked light, heat, and most magical fluctuations.
At the time, he'd thought it was flawless. He'd believed he could fool Madam Pince and move through the shelves like a ghost.
Now, looking back, that confidence felt naive.
If Dumbledore really had been watching him since last term, then there was a decent chance the headmaster already knew about those late-night visits.
But then again, if it had been noticed and never stopped, that was permission by silence.
A soft but sharp cough cut through the quiet, Madam Pince's warning.
Regulus looked up and realized there were only a few students left.
He closed the book, returned it to the shelf, and followed the last trickle of people out of the library.
The corridor lighting was dim. Most portraits were asleep, while a few were still awake, yawning in their frames or fussing with collars and sleeves.
Regulus didn't go straight back to Slytherin. He stopped at a second-floor corner, glanced around to make sure the hall was empty, then gave a small sweep of his wand in front of him.
A cold sensation washed over his skin as the Disillusionment Charm took hold.
His outline blurred, edges melting into the surroundings.
This version was his own improvement. It didn't just hide him visually. It pushed his footsteps, breathing, scent, body heat, and magical signature down as low as he could manage.
But now he suspected even that wasn't enough.
Disillusionment worked by using magic to twist light and produce a visual trick. The spell itself created a magical fluctuation, and a skilled wizard could sense that fluctuation.
The Potter family's Invisibility Cloak was a legendary artifact, said to be a gift from Death itself, one of the Deathly Hallows. Even that level of magic couldn't escape Dumbledore's notice.
In the original history, Harry Potter had wandered the castle under the cloak, and Dumbledore still called his name with perfect accuracy.
Even Snape might have noticed too, though that would be the older Snape, not the boy he was now.
Regulus walked through the empty corridor without a sound.
He needed something more complete than bending light. He needed light to pass through him as if he wasn't there at all.
Silencing sound wasn't enough either. He wanted sound not to exist, wanted his body temperature to match the environment so perfectly there was nothing to detect.
That might require altering the very state of being.
He couldn't do it yet. His knowledge wasn't deep enough, and his control wasn't refined enough.
When he reached the eighth floor, Regulus stopped.
This was the stretch opposite the tapestry of Barnabas the Barmy being beaten senseless by trolls. In the dim lighting, the bare stone wall across from it looked especially plain.
He focused, and repeated the thought in his mind.
I need a place to practice magic. Absolutely private. No one can interrupt me.
Three times.
The wall stayed empty. Nothing happened.
He'd wanted to test different methods, even wondered if pacing back and forth three times was just a ritual, and the real key was whether the room could sense a strong enough need.
But now it seemed clear. You still had to walk.
Regulus paced back and forth in front of the tapestry three times.
On the next heartbeat, a door appeared in the stone.
It was oak, fine grain running across the surface, with a bright bronze handle.
It simply existed. No sound, no flash of light, no ripple in space. It looked as if it had always been there, and he'd only just learned how to see it.
Regulus opened every sense he had. He let his magic spread outward, searching for even the faintest anomaly in the air.
There was nothing.
The door's appearance hadn't stirred anything at all. The magic in the environment was steady. The space around it was seamless, unbroken. Even the flow of air seemed to slide around the door as if it had always belonged there.
Regulus stood still, staring at it, caught in thought.
The Room of Requirement responded to a wizard's need.
But how?
If it was Transfiguration, turning part of the wall into a door with a room behind it, there should be magical fluctuations.
If it was space magic, opening an entrance in the wall, the structure of space should shift.
If it was an illusion, his senses wouldn't come up completely blank.
But he had nothing.
No feedback at all.
A thought bubbled up, uninvited. It had no proof, no logic, just something that surfaced from somewhere deep.
Maybe the Room of Requirement was always here, suspended in a state between existence and nonexistence.
When a wizard's need became clear enough, when that need was "observed" by whatever mechanism governed the room, the state collapsed into a definite reality.
The idea made his breath catch slightly.
If that was true, if Rowena Ravenclaw had designed this room using concepts that touched the deepest rules of the world itself…
Then her magic was far beyond anything recorded in later generations, reaching something almost mythical.
Regulus pushed the shock down.
He couldn't verify any of it.
He didn't even understand the room's basic mechanism, let alone its deeper design.
Some things in the magical world were simply like that.
They existed.
They worked.
You used them.
You had no idea why they were possible.
He didn't understand it, but it left him shaken in the best way.
If he couldn't understand it, then he wouldn't force it tonight.
Regulus gripped the bronze handle and pushed the door open.
Inside was a training hall.
The room was enormous, easily more than twenty meters across in both directions, with a ceiling about ten meters high, tall enough for most spell practice.
The floor was covered in dark wooden boards with a slight spring to them, meant to soften the impact of a fall.
The walls were smooth stone, carved with runes that absorbed magic, preventing spells from rebounding or damaging the structure.
In one corner, several training dummies stood, wrapped in thick leather.
In another, a wooden table held a few books and practice tools.
Clearly, this place saw regular use.
Regulus swept his eyes around. He didn't find any fresh sign of another person, but there were scorch marks on the dummies, scuffed wear on the floorboards, and a faint polish along the table's edge from years of hands and sleeves brushing past.
The Room of Requirement was secret, but not unknown.
In the original history, Harry Potter used it for meetings. Draco Malfoy used it to repair the Vanishing Cabinet. Dumbledore used it as a toilet. Plenty of students stumbled into it by accident.
Over centuries, this room had been found countless times. He couldn't treat it like a private sanctuary that belonged only to him.
Regulus walked to the center of the room and sat cross-legged.
Tonight was supposed to be simple. Confirm the location, learn the feel of the place.
But he was already here, and it would be a waste not to practice a little.
There were things he needed to test, things he couldn't comfortably do in the common room or dormitory. This place was perfect.
He reached into his pocket and drew out a single gold Galleon.
It glinted a dull gold in his palm, the ridged edge sharp and clean. On one side was the face of a Gringotts goblin. On the other, a stamped numerical code.
He set the coin on the floor in front of him, then stepped back three paces.
Spatial fold.
He'd been practicing this magic constantly, ever since Christmas, since the first time he'd managed to move a brooch five centimeters. Every day, he carved out time to try again.
Progress was painfully slow. Slow enough that most people would have called it no progress at all.
Regulus didn't mind.
Magic had never been a matter of one night's effort.
He closed his eyes and let his perception spread.
The space around the Galleon was stable, dense with tiny anchor points.
Within three meters, the structure of space formed a three-dimensional map in his mind, every node, every connection, the strength of each line.
The theory was simple. Let space fold on itself. Bring two nodes together. Pass the object through.
Regulus focused. Magic rose from within him and pressed directly against space itself.
He locked onto the node where the Galleon sat, and imagined it like a buoy on water, sliding down an invisible slope toward a nearby empty point.
His magic touched the structure. The node trembled slightly, and the air around the coin produced a ripple too fine for the eye to see.
Regulus adjusted his output, followed the natural tendency of the structure, and found the easiest point to slip in.
His will narrowed onto the Galleon. Magic stretched along the grain of space itself, driven purely by intent and power together.
The coin vanished.
There was no transition. One moment it was there, the next it was on the floor two meters away.
The placement was off. Not the target point he'd chosen. The error was nearly half a meter.
The goblin's face gleamed upward under the training hall's light.
Regulus walked over and picked it up.
The metal felt faintly warm.
Residual friction from the fold.
Which meant he had a long way to go.