Weeks blurred together in a rhythm of riot training, wand drills, and debates that burned hotter than dueling spells.
Cassius felt himself changing—pathways widening, mind sharpening, theories weaving themselves together in the quiet spaces between Grindelwald's lessons.
It was in one of those pauses, when parchment still smoked from his mentor's latest demonstration of contract-binding, that Cassius spoke up.
"I've been thinking," he began, hesitant at first.
Grindelwald, seated with his staff resting across his knees, raised a brow.
"That much I had guessed. What specifically?"
Cassius set his quill down, steadying himself.
"Muggle-borns."
"Ah." Grindelwald's voice softened into interest. "The perennial mystery. A child of no recorded magical family, and yet—magic surges awake. What of them?"
Cassius leaned forward, words tumbling out. "It doesn't make sense, does it? For magic to just… appear. Random chance? Mutation? If that's true, then any muggle at any time could awaken, and yet less than one percent of the population ever does, and even then only as children."
His hands curled into fists.
"But what if it isn't chance at all? What if it's lineage?"
Grindelwald's eyes sharpened.
"Continue."
"Old blood," Cassius said. "Ancient lines buried under centuries, millenia of marriages, forgotten, diluted until only fragments almost imperceptible remain. Passed from generation to generation like embers smoldering in ash. And then, sometimes, conditions align—the ember flares back into fire. Causing a magic riot, awakening the core hiding within, That's a muggle-born. Not new, but old blood reignited."
He paused, chest rising with excitement.
"If that's true… then all muggles carry a trace. Faint, perhaps immeasurable, but real. Which means they are not wholly without magic. Just… dormant."
The room fell silent.
As the last of his words sunk in the room ceased to produce any sound at all.
"And what," Grindelwald said at last, "does that suggest to you?"
Cassius' grin was sharp, hungry.
"What if you could wake them? Not wait for chance, not depend on bloodlines converging by accident, but—force the ember back into flame? A transfusion. A graft. A muggle technique, applied to magic. Take the power of a wizard and pass it into a muggle. See if their ember stirs."
The words were out now, reckless, dangerous.
Cassius' pulse thundered in his ears.
For a long moment Grindelwald said nothing.
Then, instead of rebuke, he laughed—a sound like iron scraping stone, dark and delighted.
"Flesh Manipulation," the old sorcerer mused. "Few dare speak it aloud. Fewer still understand its breadth. But you…"
He leaned forward, eyes gleaming.
"You are not afraid."
Cassius held his gaze.
"It isn't fear that changes the world."
Grindelwald's staff tapped against the floor.
"True. But neither does recklessness. The flesh is treacherous ground. Magic bound into blood can twist, rot, rebel against the vessel. Do you know how many horrors were birthed from experiments such as these?"
"Yes," Cassius said quietly. "But I also know what success would mean."
Grindelwald's silence stretched, then at last he nodded, slow and deliberate.
"You see further than most adults, little flame. Fewer than one in a hundred wield magic. If your theory holds, if a method existed to raise that number even slightly… revolution would not simply be possible. It would be inevitable."
Cassius' breath caught.
"Then you believe it?"
"I believe it is… worth entertaining."
Grindelwald's smile was thin, dangerous.
"But proof is everything. Theory without demonstration is smoke without fire. Tell me, Cassius, how would you test it?"
That was the question. Cassius had mulled it for weeks, twisting it over in his mind during every sleepless night.
He licked his lips, then answered.
"We can't begin here. Not yet. Too dangerous, too noticeable. But in the muggle world…" His voice dropped conspiratorially. "They have systems. Structures. Pharmaceutical trials. Volunteers who offer themselves up for tests in exchange for money. No one questions it. A new drug, a new treatment, a new chance at hope. We would only need to… insert our own candidate into that world. A controlled transfusion. A 'drug' that isn't really a drug."
Grindelwald's eyes flared with wicked amusement.
"You would use their own machinery against them. Clever. Let the muggles provide your volunteers, cloak the ritual in the trappings of science."
Cassius nodded, heart pounding.
"Exactly. And if it works—if even one muggle shows measurable signs of magic—it would prove the theory. Then, scale it. Refine it. Quietly at first, then broadly. An entire generation of awakened muggles could rise before the Ministry even noticed."
"And when they notice," Grindelwald murmured, "it will already be too late. The bridge you dream of will be built not of wood and stone, but of flesh and blood."
A shiver raced down Cassius' spine.
Grindelwald leaned back, satisfied.
"You are right, boy. This is not a question of if, but when. Flesh is not my domain—I was always more interested in fire, force, dominion—but I know enough to guide your first steps. You will study the records of the old manipulators. Learn their errors before you repeat them. When the time is right, your ties to the muggle world will supply the rest."
Cassius' mind was already racing, envisioning charts, diagrams, clinical procedures dressed up as magical rites.
A sterile laboratory hiding the oldest of secrets.
"Then we proceed?" he asked.
"Not yet."
Grindelwald's staff struck the ground with a crack.
"Ambition is a blade. Sharpen it too quickly, and it snaps. You are still a child, Cassius. A gifted one, yes, but patience must temper fire. Let the theory simmer. Build your foundation stronger. When the time comes, you will know."
Cassius wanted to argue, to insist, but he held his tongue.
Grindelwald was right.
He was four years old.
To rush now would risk everything.
But the seed was planted, and seeds, once sown, only grew.
He whispered, almost to himself: "A world where wizards are not one in a hundred, but one in ten. One in five. A world where the gap between magic and science closes forever."
Grindelwald heard, and his smile was terrible.
"A world on fire."
That night Cassius lay awake, staring at the ceiling of his narrow chamber.
His mentor's words echoed in his head, but so too did visions of what might come.
Rows of muggles lined up under bright hospital lights, each carrying embers hidden in their veins.
Embers waiting for him to set them ablaze.
Synthetic wizards.
Not born, but made.
He closed his eyes, and sleep carried him into dreams where armies of the awakened marched under his banner, wands in hand, their voices rising as one.
And when he woke, he knew with absolute certainty—someday, those dreams would be real.