"I want to go back," Elena said softly, averting her gaze from Dumbledore, studying the end of his long silver beard.
If Elena had to choose one person in the wizarding world she least wanted to encounter, it would undoubtedly be the renowned headmaster of Hogwarts School of Witchcraft and Wizardry, Albus Dumbledore.
It wasn't just because of his extraordinary magical prowess; more importantly, Dumbledore was a master Legilimens - in simpler terms, similar to Charles Xavier in the X-Men series, someone who could read minds.
Unlike most wizards who relied on spells and wands, masters of Legilimency like Voldemort and Dumbledore didn't need incantations. A mere gaze could effortlessly delve into thoughts. Hence, when someone lied to them, they could always discern the truth.
From the original works, using Legilimency seemed unrestricted by law. Snape used it while teaching Harry, and Dumbledore used it in urgent situations. Clearly, Elena didn't think Dumbledore would stoop to invading her mind.
As a time-traveler, Elena held secrets that mustn't be revealed. Ever since she woke up in the Gryffindor common room, she had been contemplating how to navigate this situation.
"You seem afraid of me?" Dumbledore's gaze swept over the girl's slightly trembling shoulders. He shrugged helplessly and gently said, "Do I look so hideous? I used to believe children rather liked me."
He grew increasingly curious about the silver-haired girl, whether it was her enchanting piano piece or her knowledge of the magical world that set her apart.
"Not fear, just a strong dislike for intrusive Legilimency," Elena said, mustering calmness, meeting Dumbledore's eyes with unwavering blue ones. Since she had reached this point, evading seemed futile; it was time to confront.
"Let's not waste time on probing and guessing. If you choose to intrude into someone's mind, then our conversation is merely another form of interrogation."
Regarding Legilimency, Severus Snape had previously explained in the original text. This became Elena's foundation for confronting Dumbledore:
"'Only Muggles talk of 'reading people.' The mind isn't a book to be read. Thoughts aren't etched on the skull; they're complex, multi-layered. Legilimens can only study minds in certain situations and offer interpretations.'"
Wizards usually believed there were two ways to resist Legilimency. The simplest was to avoid eye contact, maintain distance, reducing the success rate.
However, Elena thought this might not be as effective against a Legilimency master like Dumbledore. It would be futile as human vision encompasses a vast area of over 180 degrees; avoiding eye contact entirely meant staring with the back of one's head.
The other method was akin to Snape's Occlumency, closing one's mind against magical intrusion, allowing lies without self-exposure.
This was a targeted defense against Legilimency, but unrealistic for Elena.
In Elena's view, hiding thoughts didn't necessarily mean expelling the intruder; there was a third way.
It involved countering mystical magic with rigorous scientific knowledge.
Elena cleared her mind, recalling a complex mathematical structure she'd studied at university: Lie Group E8, one of the world's most intricate mathematical constructs completed by 18 top mathematicians over four years.
This was her only idea during her tour of Hogwarts, a possible defense against Dumbledore's Legilimency - allowing access to thoughts but preventing comprehension.
Lie Groups, invented by Norwegian mathematician Sophus Lie in the 19th century, explain the symmetry of objects. E8, proposed in 1887, is still not comprehensible by many due to its complexity.
It elucidates the symmetry of a 57-dimensional object. One of the reasons only advanced mathematicians understand - E8 itself has 248 dimensions.
She chose Lie Group E8 because while many scientific projects deal with vast data, E8's computations demand minimal input but produce immensely dense and extensive results.
In other words, Elena just needed to recall basic mathematical formulas; if Dumbledore attempted to interpret, he'd need to complete the entire derivation.
It was akin to Einstein explaining relativity; people understood the language but not its meaning.
Yet Elena went a step further, making it an arduous task. Attempting to understand E8 would entail work dozens of times greater than human genome engineering. The data generated would cover the whole of Manhattan if written down.
Human genome engineering required a billion bytes of disk space; E8 needed 60 billion bytes.
Even Hogwarts' founders, if revived, couldn't comprehend it without a high-level math background.
"A brilliant non-magical approach, isn't it?" Dumbledore, after briefly locking eyes with Elena, looked away, rubbing his forehead in mild exhaustion.
The hybrid's spiritual world was more sensitive than an ordinary wizard's, combined with the meticulously structured mathematical model. Dumbledore, after a mere glance, felt a dull ache in his brain.
More importantly, Dumbledore now intuitively realized the terrifying growth of the non-magical world - the pursuit of understanding the world's essence no longer belonged exclusively to wizards.
Regaining composure, Dumbledore reevaluated Elena by the piano.
The young silver-haired girl looked nervous, her lake-blue eyes radiating hostility, her petite frame trembling slightly, revealing her vulnerability in this unfamiliar environment.
How much fear did this child harbor towards the magical world?
Shaking his head, Dumbledore, with softened eyes, approached her, lowering himself until their eyes were level. He tentatively reached out, touching the girl's silvery hair, sincerely apologizing.
"Forgive the foolishness of an aging man."
Dumbledore's gaze softened, lacking the sharpness from before, resembling a grandfather inadvertently upsetting his granddaughter, filled with remorse and tenderness.
"As the Headmaster of Hogwarts, I promise not to use Legilimency on you again."
Elena remained silent, slightly easing her gaze. It was challenging for anyone to harbor ill feelings toward this great wizard who had permeated the entire Harry Potter series. With Dumbledore's promise as the Headmaster, there would be no breach of trust.
Seeing a slight shift in the girl's expression, Dumbledore smiled faintly, conjuring a cup of chilled lemon ice cream with a wave of his wand.
"As an apology, would you like to taste this Hogwarts kitchen's lemon ice cream? It's quite popular in your world, I presume. I'm rather fond of it."
Dumbledore winked at the silver-haired girl, offering her the dessert.
"Hmph, I'm not a three-year-old!" Elena, sensing Dumbledore's attempt to pacify her after intruding into her thoughts, feigned anger, eyeing the enticing ice cream ball. Nonetheless, she subtly licked her lips, slightly annoyed but tempted.
How could he casually intrude into her mind and try to win her over with a treat?!
Noticing the girl's reaction, Dumbledore's smile deepened. He gently took Elena's hand, placing the cup of lemon ice cream on top, speaking earnestly.
"Could you spare a little more time to hear an old man ramble?"
After a few seconds of hesitation, Elena inclined towards Dumbledore's request. As she licked the spoon, a peculiar sense of ease engulfed her since playing the piano. It felt as if she had lived in this castle for years, finding solace similar to returning to her own room.