Nine o'clock at night. Inside the Room of Requirement, Cuthbert and Alex were going at each other hard.
They'd spent the entire day goofing off, but come evening, they'd shown up on their own.
Regulus stepped out of his private cabin, took one look, and felt satisfied.
As for the daytime fun, let them have it. They were the right age for it. The Hufflepuffs could play until midnight on weekends. By comparison, these two were practically disciplined.
Hermes was on the far side of the training floor, deep in the dummy field. No wand. Just his body weaving between the enchanted mannequins.
Spells came from every direction. He twisted sideways, dropped low, slid a step left, dodged one after another.
When one was truly unavoidable, he took it on the arm, grunted as the impact sent him tumbling, then got up and kept moving.
He'd been at it all day. Morning was magic practice. Once his reserves ran dry, he switched to the dummy field for pure evasion work. Body and stamina, nothing else.
When enough magic trickled back, he returned to spellwork.
That alone set him apart from most young wizards.
Even the driven ones stopped when their magic bottomed out. Sat around waiting to recharge, or simply called it a day.
Not Hermes. He'd started filling even the empty hours.
Regulus hadn't suggested any of it. The idea was his own.
Though the inspiration probably traced back to Regulus.
That image of five spells firing simultaneously still lived in his head, vivid and sharp.
And the fact that Protego couldn't block Regulus's spells? That he remembered even more clearly.
A casual Impediment Jinx from Regulus had punched straight through his shield like it wasn't there.
If blocking didn't work, then dodge. Whether dodging would work was a separate question, but at least he had to try.
Regulus didn't stop him. Physical training was a good thing. Whether it would prove useful in a real fight, only a real fight would tell.
He thought it was necessary, though.
Muggles understood the value of physical conditioning. Why shouldn't wizards?
Because they had magic?
What happens when the magic runs out?
What happens when you lose your wand?
Can you cast wandlessly?
He pulled his gaze back and returned to the cabin.
He hadn't been here during the day. He'd spent the afternoon in the Library, picking apart the theory behind Sonorus until it gave up every secret it had.
The principle of convergence already mapped onto the Wand-Lighting Charm. Magical force acting like two walls, compressing light waves inward from both sides. The tighter the squeeze, the narrower the beam.
He could now compress it to the width of a finger, projecting a coin-sized dot on a target.
Regulus sat cross-legged. A sphere of light materialized in front of him. The Wand-Lighting Charm.
Light danced through the cabin, not quite steady. It pulsed at a high frequency, rhythmic.
Color shifts were subtle. Silver-white drifting toward pale gold now and then before snapping back.
But the frequency was changing. The brightness was changing. The intensity, the wavelength, all of it in flux.
The cabin flickered between light and shadow, and if you stared long enough, something in your mind started swaying with the rhythm. A creeping vertigo. Nausea rising.
Regulus watched the light. A thought stirred.
The sphere began to contract. Its edges drew inward, as though two invisible palms were pressing from either side, squeezing.
Narrower and narrower. Fist-width became finger-width. Finger-width became pen-width.
Until it condensed into a single thread, firing straight from his wand tip and striking the opposite wall. A pinprick of brightness. Nothing more.
The Wand-Lighting Charm was one of the most basic spells any young wizard learned. No difficulty whatsoever.
For Regulus especially. Without adding anything to it, he could reshape it however he pleased.
But layering something into the light changed everything.
This Light Source Magic used the Wand-Lighting Charm only as a foundation, and not even an irreplaceable one. Swap in a different illumination spell and the result would be roughly the same.
It couldn't be described as advanced magic in the traditional sense. It was composite magic. Extraordinarily complex.
The Wand-Lighting Charm formed the base, but what had been woven into it couldn't be defined as any specific spell.
Because the encoding of information into light wasn't incantation-based. It was technique, achieved purely through raw magical manipulation.
It could be replicated. It could be learned. But it had no complete spell structure.
Powerful magical perception and precision control were the foundations for both beam convergence and information encoding. Without sufficient perception, you couldn't detect the light's variations. Without sufficient control, you couldn't calibrate frequency and phase.
Occlumency served as a critical support. During development, it stabilized his own mind, walling off external interference.
He'd also used it to carve out quarantined zones within his consciousness, storing samples of extreme, pure emotion inside them, then crystallizing those samples into stable structures with sheer mental will so they could be called up at any time.
But that wasn't the decisive factor. The real breakthrough came from his deconstructed use of Legilimency.
Regulus had taken Legilimency apart, extracted the components governing mental targeting and connection-building, and adapted them so that encoded information could be delivered through light into the surface layer of a target's consciousness.
That part relied not on magical power, but on exploration and understanding of the mental domain.
Then there was the physics of light and waves. Muggle science. Wavelength, frequency, amplitude, phase.
Translate those into magical terms and they became the density of magical oscillation, the intensity of spell energy, the directional bias of emotional resonance.
And at the root of it all, the Patronus.
Regulus used the Patronus's magical texture as a bonding agent, forcing the naturally repellent energies of Legilimency and the Wand-Lighting Charm to hold together.
The Patronus was, in truth, the key inspiration and theoretical cornerstone that elevated this Light Source Magic from simple beam manipulation into a carrier of information and concepts.
Finally, his own growing strength of will. That was what held every piece in place and let him walk through each step without it collapsing.
All of it together. That was what pulled this magic out of his head and turned it into something real.
Regulus dismissed the light sphere. The cabin went dark, with only the dim overhead lamp swaying its glow across the walls.
This was still the initial testing phase. Plenty of problems remained.
But he could start by shifting visible light into the invisible spectrum. Ultraviolet would work nicely. Invisible to the naked eye, and it aligned with the Compressed Light concept he'd already mapped out.
Push the wavelength down past the visible threshold, into the ultraviolet band. The target wouldn't know they were being hit. That was what a proper ambush looked like.
Magical perception could probably still detect it, though. Another problem to solve.
After that, more complex applications. Pack in more information. Emotional detonation. Psychological penetration.
One beam of light, and the target's mind overloads. A brief shutdown.
Or sustained exposure, amplifying whatever psychological cracks already existed, nudging the target toward their own extremes.
The cautious become cowards. The competitive become reckless.
Fear, excitement, contempt, trust, impatience, arrogance. All usable.
And then the broadcast version. Light that didn't just converge but dispersed. As wide as possible.
Battlefield application: hurl a sphere of light into the sky. It detonates. The glow blankets the entire field.
Allies see the light, and trajectories of incoming curses bloom in their minds. Which zones are about to spawn new threats. Which spells to use in coordination with their partners.
No shouting. No owls. Zero delay.
Enemies see the same light, but they receive something else entirely. Fear, hesitation and chaos.
One beam. Two payloads. Allies get clear tactical instructions. Enemies get emotional sabotage.
He becomes the command center.
He'd even thought further than that.
If this magic truly matured, then he wouldn't be limited to pushing emotions and thoughts into people's heads.
He could do more. Go more abstract.
If he could scatter light through the atmosphere, blanketing the globe in a fraction of a second, he could transmit information simultaneously to every human being who could see light.
The corner of his mouth twitched.
If that day ever came, what should he say?
I, Regulus Black, am speaking to the entire world.
Not bad.
He shook his head and tossed the image out of his mind.
That was exactly why Aragog had to keep quiet. The fear was that Dumbledore might learn of this and start thinking too hard about it.
One flash of light and a new thought appears in the target's mind, seamlessly disguised as their own.
If anyone guessed the ultimate potential of this magic, he'd become the single greatest threat to the Statute of Secrecy.
Muggles didn't know wizards existed because wizards hid well.
But if one day, a single wizard could make every Muggle on Earth simultaneously see the same image, hear the same words, think the same thought...
Then what was left to hide?
How would you even try?
The entire order of things would be rewritten overnight.
So keep it hidden. Work in secret.
Another image surfaced in his mind.
What if, one day, he announced to every wizard alive that Voldemort was the product of a love potion? What kind of fallout would that cause?
Or scatter some other rumor. That could be entertaining, too.
He stopped himself from going further down that road and turned to testing the Spatial Network.
---
He stood up and pushed the door open.
Hermes was flat on the ground, limbs splayed, chest heaving.
Cuthbert and Alex were still in the dummy field, hanging on, but their footwork had gone shaky and their spells were flying wide.
Regulus called a halt. The dummies froze. The two of them staggered over to where Hermes lay, dropped down on either side of him, and went rigid.
Three bodies in a row, waiting to be collected.
Regulus looked at them, flicked a finger, and all three floated off the ground.
He drifted them all the way back to the dormitory, left them on the floor.
Cuthbert was first to get up, stumbling toward the washroom. Alex was slower. Hermes moved last.
Each cleaned up in turn and crawled into bed. The fire in the hearth was still going.
"Alex," Regulus said.
Alex turned his head. "Yeah."
"Tomorrow at noon. Tell Samuel and Lina to come meet me at the Great Hall. I need them for something."
Alex went still for a moment.
At the start of term, Regulus had told him to keep Samuel and Lina under the radar.
He hadn't known exactly why, but he'd followed the instruction. Some vague sense that it tied to things happening outside Hogwarts.
Otherwise, two half-bloods who hadn't even warranted a second glance during recruitment wouldn't have merited a personal reminder from Regulus.
Then came the Chief contest, and those two had run an errand, fetching Professor Slughorn.
In the last Defense Against the Dark Arts class, Regulus had paired Cuthbert and Alex with them for practice.
"Alright," he said.
Cuthbert was too exhausted to speak up, though normally he'd have jumped in wanting to be part of it.
He lay still, but his eyes darted around, scheming about something. He traded a glance with Alex, and both looked away.
Hermes faced the wall, breathing steady. Whether he was asleep or not was anyone's guess. He never cared about this kind of thing.
The flames in the hearth gave a few last flickers and died.
The dormitory went dark.