The golden light flared so brightly that it painted the chamber walls in fire.
Cassius blinked against it, his hand trembling, but the wand obeyed.
The flame was richer, warmer, than the pale Lumos he had seen demonstrated.
It carried weight, resonance, as though the magic itself recognized the word.
Grindelwald leaned forward in his chair, mismatched eyes sharp and predatory.
"What did you say?"
Cassius swallowed, lowering the wand just slightly.
"Calad. It means light. But not in Latin. In… another tongue."
Grindelwald's lips curled, half sneer, half smile.
"Seems to have been a more magical language than latin, or any other i have seen used before."
Cassius shook his head.
"A language of fiction, in the muggle world. Elvish. It was the creation of an author who wrote during your time, it was the spoken language of a pure magical race."
The light flickered once, then dimmed, fading back to an ordinary glow before vanishing altogether.
Grindelwald's staff tapped the stone floor once, the sound echoing.
"Fascinating. A false tongue conjured by a mortal, yet magic answers. You may have stumbled upon something most wizards would dismiss outright."
His gaze sharpened.
"Do not dismiss it yourself. Words are bridges, and power flows through bridges unseen. Continue with this experiment."
Cassius nodded, though a smirk tugged at the corner of his lips.
It was a victory, however small—a proof that his instincts about innovation had teeth.
Grindelwald saw the smirk, and his own expression cooled.
"But power, no matter how bright, is meaningless without direction."
He leaned forward, fingers steepled.
"Tell me, boy. You speak often of plans. Of roots in both worlds. I have heard your frustrations whispered even when you think yourself silent. Speak plainly now. What is it you seek?"
Cassius froze.
He hadn't expected the question to come so soon—or with such weight.
But the fire still burned in his chest, and holding back was impossible.
"You want to know my plans?" he said, voice sharp. "Fine. The muggles are simple. Easier. Show them something shiny—some new invention, some new flavor of progress—and they'll rush to it like children to sweets. They don't care if it's dangerous or untested. They crave novelty."
He stood now, pacing, unable to keep still.
"But the wizarding world? It's the opposite. Stubborn. Proud. Arrogant. They sneer at innovation, pretend their old ways are sufficient, are superior than muggles. I tried. Merlin knows I tried. Introduce something useful, something transformative—and they block me. They cling to stagnation like it's sacred."
His voice rose, bitter and hot.
"They're a century behind the muggles, Mentor. A hundred years! Electricity, engines, medicine, communication—they sit in the dark while muggles split atoms and fly across oceans in hours. And still the magical leaders puff their chests, as if refusing progress makes them superior. It makes them fools."
Grindelwald said nothing, only watched.
Cassius' fists clenched.
"Yes, I could make money. Recipes, potions, little trinkets to sell at Diagon Alley. Enough to fill a vault, maybe a dozen. But gold is nothing but a leash. Real change—lasting change—will never come from coin alone. It requires a shock. A fracture deep enough to break the old guard's hold."
He stopped pacing, turning sharply toward his mentor.
His eyes glowed with the force of his conviction.
"The shake up will come from an enemy, Voldemort, but to me he shall be but a tool, an instrument to rid the magical world of the leaders and bureaucracy to which has caused it to idle and stagnate. I will reshape Hogwarts itself. Update the curriculum. Teach wizard-borns the truth of the muggle world—not fairy tales, not distortions, but science. Real theory. Real knowledge. And at the same time, teach muggles that their science can coexist with magic. That the two are not opposites, but mirrors. To them, magic is just the part of science they cannot yet explain."
The last words hung in the air like thunder.
For a moment, silence stretched.
Cassius' chest rose and fell with each ragged breath, the tirade having ripped itself out of him with a force he hadn't intended.
Then, Grindelwald laughed.
It was not cruel, nor mocking, but low and rich, a sound like dry wood catching flame.
"You burn brighter than I expected," the old man said, leaning back. "Do you know what you sound like, boy?"
Cassius scowled.
"A fool?"
Grindelwald's grin sharpened.
"A revolutionary."
He stood, staff clicking against the floor as he circled Cassius slowly.
"You think you are the first to see wizardkind's arrogance? You are not. I saw it. Albus saw it. Even Tom—though he twisted the vision into something monstrous—saw it. But you, ah…"
He stopped, meeting Cassius' gaze.
"You are the first I have heard who speaks not of domination, but of integration. A bridge. Two worlds, not one destroyed to feed the other."
Cassius straightened, feeling the heat of those words.
Grindelwald's tone softened. "But bridges are fragile things. They must be built carefully, stone by stone. Too fast, and they collapse. Too weak, and they are washed away. You wish for a shake-up? Then you must learn to choose your earthquake. Too small, and no one notices. Too large, and all is reduced to rubble, including you."
Cassius nodded, though his jaw was tight.
Grindelwald's hand, veined and trembling with age, reached to tap him lightly on the chest.
"but first we must create your own foundations, a magical life is a long one, you are still very young, there will be plenty of time to increase your influence on the muggle world, you would be surprised at just how much power the muggle governments already have over the magical one. Gain control of britains parliament and you can exert pressure on the Ministry of Magic to make a move even if they are unwilling to do so."
the lessons that followed were no less intense, only they had an additional component, debate discussions regarding the dark arts, as well as defense against the dark arts.
Cassius's stance was that all magic is just that magic, dark arts were a section of charms, but it was specific wizards who make the dark arts evil.
Grindelwald alternatively rebutted that the dark arts are in fact evil, not refuting Cassius's point since he was right, but at the same time, there are parts of the dark arts that were created that could only be seen as evil.
Such as Flesh Transfiguration, which often requires sacrifices sometime human, or causing mutation in humans the spells or rituals are cast upon.
In fact most magical creatures alive today were created thanks to dark wizards uses of flesh manipulation.
Then there are forms of magic transfiguration which touch upon flesh manipulation where magical creatures are merged with a human to gain its power and thereby inhance the humans magic power and potential.
Cassius agree's but then also debates about the lack of training wizards receive in the dark arts while also questioning the unforgivables themselve.
Grindelwald for all his suffering over the years could only feel new life being breathed into him, he had foudn a true heir through his waiting.
Not even Albus or himself were this precoucious in their youth, and yet here was Cassius was unravelling the mysteries of magic at the tender age of 4 concepts the pair hadnt started to do until their 20's.