The world snapped back into focus with a thunderclap of displaced air.
Cassius landed lightly on the marble floor of his London flat—a quiet condo tucked above the Muggle world.
To anyone else, it was an unremarkable property: three rooms, high ceilings, steel and glass and shadow.
But beneath the veneer of modernity, it was a fortress. Grindelwald had made sure of that.
The wards hummed the moment he appeared.
They recognized him instantly—sliding around his presence like silk, warm and weightless, their touch whispering across his skin before fading into invisibility once more.
These weren't simple household wards.
They were old magic, layered in threads of secrecy and deflection.
To Muggles, the condo didn't exist.
Like that episode of Doctor who where the flat using a perception filter had a second floor when there wasnt one.
To the Ministry, it was an empty, dead zone of static.
Even Dumbledore himself would need time to unravel the spacial disturbance to find the condo, making it even harder to breakthrough than a fidelius charm.
Cassius set his bag down on the counter and exhaled.
The flat was silent, save for the faint hum of the wards and the steady rhythm of the city far below.
The soft blue glow of enchanted sconces reflected against the glass walls, bathing the space in shifting light.
He reached into his cloak and withdrew both wands.
The agarwood and true dragonheart—ancient, regal, vibrating faintly with the weight of history.
His true wand.
And the yew and thunderbird feather—newborn and volatile, alive with stormlight.
His mask.
He laid them side by side on the counter, studying the contrast: one pulsed like a deep heartbeat, the other flickered like lightning trapped in amber.
"Two halves," he murmured, "of the same intent."
'the duality of my very own soul.'
He had returned from Nurmengard not as a student, but as an apprentice in truth.
Grindelwald had given him freedom, and in return, Cassius would refine himself into something formidable—something inevitable, bringing about his mentors dream one day, though perhaps not in the same way his mentor himself had tried decades before.
By nightfall, the condo was no longer a home.
The books Cassius had studied excessively so were now floating freely in the air, as the living room itself became his new practice field.
A few wooden dummies being taken from his bag setup with an auto reparation function, so Cassius could go all out against them if he wanted.
By the time the room was setup just perfectly for him, it looked more like the setup of an actual battlefield.
The living room had been expanded, using the undetectable extension charm to be many times larger than before, and on top of that even rubble had been placed to make it up to simulate a proper battlefield.
Then the real training began.
He started with the fundamentals.
But his mentor has a little surprise in store for him.
"Expelliarmus."
The red light shot across the room, sharp and controlled, almost slamming into a practice dummy.
Only the dummy moved at the last minute out of the way, but just that single cast was like hitting the start button, across the field six dummies quickly set off racing along as if they were running ducking and darting amonst the rubble.
"Protego."
A faint shimmer of blue caught a flash of yellow sent towards him, the air rippling faintly with heat.
He adjusted his stance, feeling the pulse of both wands alternately in each hand—the older one heavier, deeper in resonance; the thunderbird wand lighter, quicker, eager to move.
Each spell flowed differently between them.
The yew wanted aggression—it thrived on offense, on momentum. The agarwood demanded precision, grace, restraint.
So he learned to switch between them seamlessly.
One hand flowing into the next, each casting like a phrase in a larger language.
Even with this being his only second ever 'fight' Cassius was putting up a stiff resistance whilst outnumbered.
But in the end he still lost, unable to overcome this but quickly resetting after coming to from being hit by the dummies stunners.
Hours passed.
It was only the first real day of possessing and training with his wands, and already he had instinctively begun to silently cast during his mock battles, the learning curve was steep since the pain he felt within those battles was very real.
'Lumos'
Chanting out the word in his the tip of both his wands lit up with an intense light at the peak of the lumos basic spell.
He shifted the focus in his mind—pushed the emotion, the meaning of the spell.
The light deepened, twisting until it burned green once more.
He allowed himself a small smirk.
The false Killing Curse.
It had saved him once already.
Then, with a quick motion: "Diffindo."
The air sliced cleanly through a hanging tapestry, cutting it in half with surgical precision.
He spent the next hours like that—building reflex and rhythm, chaining spells until they became instinct.
Disarming, shielding, slicing, blasting.
His dueling style grew sharper, more serpentine, built for deception and control.
All while dozens of spells found their way onto his system list, before he quickly started to assign them into his idle slots, he had less than a month to train before he would be sent off to school, and he needed to be ready, sure the spells could develop further while there, but there is a difference between being a genius and becoming a genius.
And it wasnt just first year spells either, Cassius had already begun to dip his toes all the way into fourth year spells.
Seeing as how the first year curriculum really doesnt cover any real attack magic or how to deal with it, at least not yet it doesnt, Cassius felt the need to far surpass his peers to prepare for possible bullying caused by the upper years, since as the leader of new dawn it was his position to protect those he had sent into the school ahead of him.
He wasn't just preparing for Hogwarts.
He was preparing for everything that came after.
Voldemort was only a stepping stone, the real challenge within Britain would be Dumbledore and if he was provided with proper training possibly even Harry Potter himself.
But as it stood right now, unless someone was prepared to smack down an 11 year old child, Cassius would be practically uncontested for those of the same age, or even a year above himself.
At midnight, he stood on the balcony overlooking the dark stretch of the Thames.
The entire day had been spent in one simulated battle after another, and even after only this one day Cassius had more battle experience than most of the adult wizards currently residing within the isles and he still had just under a month to continue gaining furhter experience beyond what his system could provide him since simply knowing a spell is not the same thing as knowing how to fight with those spells.
By the time Cassius even set foot on the hogwarts express he wanted to make sure that even if he were to participate in a 15n under duelist competition he would be completly unmatched.
Cassius had a mentor to live up to at the very least, and a man who for close to the last ten years has run his backside ragged with intense training and the true graduation test would not be complete until after he'd managed to lay his own mentor old though he might be on his backside in return!