Regulus didn't stop moving. His wand flicked toward the corroded hem of his sleeve, a flash of light, and the decay halted. But the drain on his reserves was real.
He fired a silent Expelliarmus. The red light slipped through the thinning edge of the mist, concealed, aimed at Orion's chest.
Orion sidestepped and brought his wand down in the same motion.
Blue light streaked toward him. Regulus triggered the Side-Shift Spell and blinked aside. The curse struck the wooden training dummy behind him, which crumpled to the floor like a puppet with its strings cut.
His feet hit stone and his wand snapped upward. "Reducto!"
The curse tore toward Orion's upper body. Orion arched backward, letting it scream overhead and slam into the ceiling. Runes blazed white where it struck.
He exploited the fractional pause after Regulus's cast, wand jabbing forward. "Petrificus Totalus!"
The Body-Bind came fast. Regulus managed half a Side-Shift, and the spell grazed his left shoulder.
His arm locked rigid. He forced raw magic through the frozen muscles, breaking the petrification from the inside, but the effort cost him half a beat.
Orion pounced on the opening. Three Impediment Jinxes in rapid succession walled off every retreat, and his wand rose high. "Stupefy!"
The red light of the Stunning Spell blazed in a straight, searing line.
Regulus was boxed in between the translucent barriers of the Impediment Jinxes, his movement space shrinking by the second.
No panic. His wand stabbed downward.
The stone tiles beneath his feet collapsed inward. His body dropped with them, and the Stunning Spell sailed over his head.
He vaulted out of the crater. His left arm still tingled with residual numbness, but it obeyed him again.
Orion was pleased with the mobility Regulus had shown.
He recognized every movement spell in the boy's repertoire: the Side-Shift Spell, the Swiftness Spell, the Flight Spell, the Sprint Spell. All of them were straight out of the Ministry of Magic's Auror training manual.
But the way Regulus chained them together was seamless, as natural as breathing. Maintaining spell output while repositioning at speed required more than talent alone.
That demanded relentless practice. Cooldown windows, mana costs, movement arcs, all of it drilled into muscle memory until the body moved before the mind could think.
Regulus had said his progress was modest. Looking at it now, modest was an understatement.
In terms of direct combat ability, setting aside certain high-tier magic, Regulus was already approaching elite Auror standards. Two years ahead of Orion's most optimistic projections.
And he knew Regulus was still holding back. The three Unforgivable Curses, Fiendfyre, the Patronus, Spatial magic, Verdant Magic... none of those had made an appearance.
Orion's thoughts drifted for only an instant before he reined them in.
Against the Regulus standing in front of him now, even he couldn't afford the luxury of a wandering mind.
On the floor, Regulus had identified the problem.
The fight had settled into a classic high-defense, low-offense deadlock. Both their Protego barriers were too strong for standard spells to penetrate. Both were mobile enough to avoid being pinned down.
If he let this drag into a war of attrition, reserves and stamina would decide it, and Orion would win that contest every time.
He needed to break the stalemate.
The Unforgivable Curses were unforgivable for a reason, and one of those reasons was that they couldn't be blocked.
Protego was useless against the Cruciatus. Even more useless against the Killing Curse.
The Cruciatus could be endured through sheer willpower, and the Killing Curse could be dodged or intercepted with a physical object. But both sailed clean through that silver barrier as though it didn't exist.
After another Confringo, Regulus's left index finger flicked with a subtle, almost invisible motion.
A hair-thin thread of scarlet shot from his fingertip, silent, lost in the bloom of fire and the swirl of smoke, arrowing toward Orion's chest.
The Cruciatus Curse.
Orion's brow furrowed.
His body vanished.
Regulus analyzed the disappearance in a fraction of a second. Not a Disillusionment Charm. Not high-speed movement. Not spatial magic.
Orion had truly vanished. Even his magical signature had winked out of existence.
In the same instant, the training room plunged into absolute darkness.
His eyes still worked. Nothing had been done to his vision. But every photon of light in the room had been swallowed whole.
The protective runes along the walls went dark. The torches on their sconces died. Even the faint residual glow at the tip of Regulus's wand was devoured.
The blackness was so dense it felt solid. He couldn't see his own hand. Couldn't see his own body.
Shock registered and was immediately filed away. The Side-Shift Spell fired, sliding him five feet left, landing without a sound.
His left hand rose. "Lumos Maxima!"
The enhanced Light Charm coalesced in his palm, bright enough to illuminate the entire training room under normal conditions.
The sphere formed. Its light reached half a meter from his body and hit a wall.
A wall of darkness.
At the boundary, light and shadow ground against each other. He could see tiny flecks of radiance being consumed at the edge, dissolving the way snowflakes vanish when they touch flame.
Regulus killed the light immediately. The sphere couldn't extend his vision, but it would betray his position.
With light suppressed, sight was useless. He closed his eyes and opened his magical senses to their fullest range.
The result was worse than expected. His perception had been compressed to a fraction of its normal reach.
A range that usually covered dozens of meters now stopped at five. Beyond that boundary: nothing. A void, unreadable. Within it, even the impressions that did register were blurred, distorted, stripped of detail.
No time to analyze further. The attack came.
No warning, no origin point. A Diffindo materialized three meters to his right, the silver arc slashing toward his throat.
Regulus twisted aside. The blade of light grazed his shoulder, slicing a clean gash in his sleeve.
Before he found his footing, an Impediment Jinx rose from the floor on his left, a translucent wall sealing off his retreat.
He launched upward. The Flight Spell caught him, suspending him in the air as an Incendio swept the ground beneath his feet. Heat roared upward and scorched the soles of his shoes.
Orion's spells came from every direction, their origin points random, following no pattern.
One second the attack struck from the front. The next it materialized behind him.
Regulus could rely on nothing but his five-meter sense radius for early warning, chaining his movement spells into evasive combinations.
Too passive. Far too passive.
His mind went to the ancestral magic of the family. Cassandra Black, twelfth-century ancestor, the one who had left behind the Shadowstep Charm.
That spell let the caster meld with shadow, achieving true invisibility and short-range teleportation through darkness itself.
The oppressive blackness smothering light and perception around him now might well be a variant application of that same ancestral legacy.
Regulus tried summoning his Patronus.
"Expecto Patronum."
Silver-white light gathered at his wand tip. The silhouette of the Starlight Kite sharpened into focus.
The moment it appeared, its radiance pushed the darkness back in a small radius, clearing a two-meter sphere around him.
He sent the Patronus outward.
But the instant the Starlight Kite passed beyond the two-meter boundary, he lost all sense of it. Whether the connection had been severed or his perception was being blocked by the darkness, he couldn't tell.
He tried to recall it. No response. He canceled the spell manually, and the Starlight Kite dissolved into scattering motes of light.
Darkness closed in again.
Sirius stood at the doorway, frozen solid.
His mouth hadn't closed since the fight began.
What Regulus and Orion had done in that room bore no resemblance to anything he'd imagined a wizard's duel could be.
It wasn't students trading hexes in a corridor. It wasn't two people standing their ground and hurling spells until one side's reserves gave out.
It was real combat. High-speed repositioning, tactical deception, environmental manipulation, spell combinations flowing one into the next.
He'd watched Regulus dodge a Diffindo with the Side-Shift Spell and chain seamlessly into the Swiftness Spell to open distance. Watched Orion absorb an Expulso with his Protego and immediately pour reinforcement magic into the barrier to keep it standing.
He'd seen them use Impediment Jinxes, Incendio, and Expelliarmus to cut off each other's movement lanes at ten-meter range. Seen Regulus vault a wall of fire with the Flight Spell and loose a Confringo from midair.
Every movement was precise. Every spell had a purpose.
No flourishes. No showmanship. Pure efficiency and lethality.
What stunned him most was how they cast. Half the time a spell left the wand, the tip wasn't even pointed at the opponent.
Orion had thrown a Diffindo from his hip, the arc curving around Regulus's frontal defense.
Regulus had aimed a Confringo at the floor, using the blast and debris to disrupt Orion's footing and break his next cast.
Spellwork like that didn't exist at Hogwarts. Not in any class, not in any duel he'd ever seen.
Then the darkness came.
A blackness so thick it felt physical, swallowing the training room whole.
Sirius couldn't see a thing inside. Sound had vanished too, absorbed and sealed away by the dark.
All he could hear was his own ragged breathing and the hammer of his pulse.
He couldn't look away. His eyes strained wide, searching the blackness for anything: a flicker of light, a hint of movement.
The ache beneath his ribs was forgotten. Only one thought filled his head.
What's happening in there?
Is Regulus done for?
What kind of magic is Father using?
How long the darkness lasted, he couldn't say. Time stretched in the waiting, each second pulling taut into a minute.
Inside the dark, Regulus moved at speed.
Sight was gone. Magical perception was crushed to five meters. All he had was that narrow warning radius, probability, and luck to find Orion's position.
He cut through the training room in erratic patterns, chaining the Side-Shift Spell into the Swiftness Spell, pivoting on contact, accelerating with the Sprint Spell, occasionally throwing in the Flight Spell to change altitude.