So, what was Grindelwald truly like at fourteen?
Let's use a few comparisons.
Snape had already mastered quite a number of curses before even entering Hogwarts, and by his fourth and fifth years, he was creating original dark spells of his own. Silent casting, at that stage, was hardly a challenge for him.
Voldemort, at fifteen, had already forged a Horcrux—undeniably the most dangerous student Hogwarts had ever seen.
And Ariana? She had died the very year Grindelwald was expelled from Durmstrang. At that time, the spells he and Albus Dumbledore were wielding could already inflict lethal damage. The level of their magic spoke for itself.
So, if you roll the clock back just two or three years, his strength would've dipped slightly—but even then, Grindelwald remained the kind of prodigy normal wizards could never hope to comprehend.
Ariana's painstakingly practiced wordless Blasting Curse was flicked aside with casual ease, dissolved in a single sweep of Grindelwald's wand.
Light flared again and again between them—shimmering shields, bursts of color, the glow of a Shield Charm intercepting spells, Ariana's sharp little voice echoing as she chanted incantations.
Grindelwald, however, seemed to stroll through it all with unhurried poise. He countered her strikes like he was brushing dust from his sleeve, weaving effortlessly through the battlefield.
Andros shook his head helplessly.
It's still too soon. She's only been learning magic for just over a month. How could she possibly hope to beat him?
The only mercy was that Grindelwald hadn't ended it in a single move.
But Andros quickly realized even that "mercy" was dangerous.
When Ariana exhausted her little arsenal—her three main tricks already cast, her breathing ragged—she faltered, not knowing what to do next. That was when Grindelwald's expression sharpened.
"Avada Kedavra!"
The words rang out, cold as death.
Green light seared across the dueling field. Ariana froze where she stood, her soul nearly locked in terror as the Killing Curse shredded her counter-spell and surged toward her. Her wide eyes reflected the emerald blaze.
"You've lost, Ariana." Grindelwald's voice carried like steel through the study space.
The girl stood rooted, stunned into silence.
Tom scowled. "Oi, Grindelwald—that's a bit much, isn't it? Forget whether you even knew the Killing Curse in your fourth year. Even if you did, was it really necessary to scare her half to death with it?"
"You spoil her too much." Grindelwald sneered sideways at him. "It's just the Killing Curse. I had it under perfect control by my second year. And you're worse—you mastered it in your first, didn't you?"
Tom waved his hands quickly. "That's not the point. You shouldn't be teaching it in the first place—"
"You forced me to teach you. You saying you had to learn?" Grindelwald scoffed, then turned back to Ariana. "Besides, I said before the duel even began—I wouldn't hold back. Even against her. That's respect.
"Ariana doesn't need a false victory." His gaze hardened. "I'm right, aren't I?"
Tom reached for Ariana's trembling hand. The warmth steadied her, and after a long breath, she nodded.
"It's just the Killing Curse… and I'm already dead anyway. I'm not afraid." Her voice grew firmer. "Grindelwald, just wait. One day, I will surpass you."
It seemed Ariana had finally broken through her old fear—she could even throw defiance back in his face.
But Grindelwald shook his head.
"Ariana, I've gauged your level now. Frankly… I don't believe you'll defeat me any time soon. At this pace, it would take you two or three years just to reach my fourteen-year-old self. And don't forget—every year, I too will grow stronger."
Her face blanched. She looked desperately toward Tom and Andros.
"Well…" Andros scratched his head, a bit awkward. "Grindelwald specializes in Dark Arts. The thing about dark magic—it's fast. Much faster to gain power early on than ordinary spells. But don't worry. You've got advantages he never had: this study space, the Meditation Chamber… you'll catch up."
Tom nodded soberly. He couldn't lie to her. He remembered how, not long ago, even a dragon had nearly overwhelmed him. But after meeting Grindelwald and learning a few Dark Arts? He had crushed a Hungarian Horntail with ease.
Dark magic was like cultivation in the old tales—ruthless, risky, but brutally efficient.
"Th-that's unfair…" Ariana's lip trembled, her eyes misting. "I knew there was a gap, but I didn't think it was this wide… Two, three years? By then, Tom will already be who-knows-where… I'll be useless!"
"I can help you."
The words cut across her despair. Grindelwald's voice was calm, certain. Ariana blinked, startled.
"You… help me?"
"Yes." He nodded. "Andros can remain your teacher, but I can be one as well. Who knows me better than myself? Not even Albus. If you want to defeat me, I'll teach you how—teach you where I'm weak, how I fight, how to counter me."
"As for Andros—" Grindelwald cast a dismissive glance. "His style doesn't suit you. Much of what he teaches simply isn't aligned with your gifts."
"And what would you teach me?" Ariana whispered. "Dark magic?"
"Of course." Grindelwald's eyes glinted. "No one becomes truly powerful hobbling on one leg. Don't interrupt me, Andros!" He snapped, glaring when Andros opened his mouth.
"Ariana doesn't have your monstrous talent," he continued harshly. "Her path can't be like yours. She must walk the same road I once did. The road Albus walked. The path of a true wizard."
Tom stroked Ariana's hair gently. "Whatever you choose, Ariana—I'll support you."
Grindelwald didn't rush her. He simply waited, patient, confident she'd see the truth.
Neither he nor Tom nor Andros said aloud the final thought they all shared:
Compared to ordinary spellwork… Dark magic was Ariana's true calling.
Born with an Obscurial's shadow inside her, her body housed an immense reservoir of dark power. With the right guidance, that darkness wouldn't consume her. It would elevate her. She wouldn't just be another witch. She could become terrifying.