In the tale of Le Morte d'Arthur, the Holy Grail also appeared covered by a white cloth, but it manifested alone in the Throne Room where the Twelve Knights of the Round Table had gathered.
Upon its appearance, it provided Holy Communion to each knight before circling the hall and vanishing.
Afterward, all the Round Table Knights, except for the King of Knights, became obsessed with finding the vanished Holy Grail. Ignoring the King of Knights' objections, they collectively took their leave to embark on the Holy Grail Quest.
At the quest's conclusion, it was Galahad who found the Holy Grail, but his wish was for the Grail to take him to Heaven.
In the future Guinevere knew, nearly all stories praised this quest and lauded Galahad as the purest of the Holy Grail Knights.
But now, seeing the Grail with her own eyes, watching the knights in the tent gaze at it with spellbound reverence, and struggling against the soul-sucking pull that seemed to target her alone, Guinevere couldn't shake the feeling that the Grail was nothing but a conspiracy.
The Holy Grail Quest, so celebrated in later ages, was likely the true beginning of the Round Table's collapse. It had taken Galahad away and sown the first seeds of discord between the King and her knights.
"Guinevere, you look unwell. Is there something wrong with the Grail?"
While everyone else was dazzled by the Holy Grail, the King of Knights was the only one, besides Guinevere, who remained unmoved—just as in the tale of Le Morte d'Arthur.
Her gaze lingered on Guinevere, wondering why she had insisted on obtaining the Grail.
Noticing Guinevere's distress, the King of Knights immediately took her hand, transferring her own warmth to Guinevere.
As the King of Knights grasped her hand while she was in a daze, Guinevere turned back and smiled at her, silently cheering herself on.
She had realized it: the Grail's soul-sucking pull targeted only her; everyone else was merely captivated. In that case, she would find out exactly what conspiracy was at play here.
"Lia," Guinevere whispered, leaning close to the King of Knights' ear, "if I die, I want you to slaughter every last member of the Church."
Seeing the King of Knights' face instantly pale and feeling her hand tighten fiercely, Guinevere burst out laughing.
"Lia, I'm just teasing. I would never die in a place like this."
She knew that touching the Grail now, knowing it targeted her alone, was incredibly risky. Yet a feeling had taken root in Guinevere's heart: the Grail had already latched onto her. She had no choice but to confront it.
So, her only option was to approach it boldly and tear a path through the world's malice.
Without this confidence—this arrogance—she would never have accepted the King of Knights' marriage proposal. She would have long since retreated to her family estate to farm and play.
Let's see what this damn cup can really do, and what schemes the Holy Church has woven into it.
As Guinevere drew near, perhaps sensing her resolve, the Grail's pull on her soul vanished. The nun holding it raised the cup high before her.
"Queen Guinevere, Lord Noy has a message for you."
The nun's voice resonated only in Guinevere's mind, though Guinevere's own words would be heard by everyone in the tent.
"He says you have strayed far enough down the path of defying fate, even attracting the aid of those two Wanderers.
"But for Proper Human History, the past, present, and future exist simultaneously. Its key junctures cannot be altered, lest the Human Order collapse and the future be severed.
"Lord Noy says he will yield to Camelot for twenty years, following the flow of destiny. In return, he hopes you too will embrace your fate—to become the Wicked Queen who brings ruin to the Round Table.
"He also says you may ask the Holy Grail your question without fear. Your time of departure is not now."
"Your Lord Noy talks too much."
As the King of Knights stepped forward once more to take her hand, Guinevere considered for three seconds before reaching out to touch the Holy Grail.
In an instant, her vision went black. When she opened her eyes again, she found herself in a realm of pure white. She didn't know where she was, only that she felt infinitesimally small and understood it was her turn to ask.
"Tell me," she began, her voice echoing through the white expanse, sending ripples across its surface until a spectral vortex materialized. "Has the fate of the King of Knights and I been changed?"
As Guinevere reached into the vortex, she realized it was composed of countless worldlines. The Holy Grail was showing her the futures of myriad worlds.
Among these infinite worldlines, anomalies like her were rare, and a worldline containing her was utterly unique.
This meant Guinevere had her own independent stage—she truly could script a different play.
But as this realization dawned, the smile vanished from her face. She was in the genuine Proper Human History.
The play she was destined to perform already had its opening and final acts set in stone.
The opening act was her arrival. The final act was the death of the King of Knights. No matter how brilliantly she danced during the performance, the finale could not be changed.
And if that finale were changed...
A minor alteration would create a Singularity, which the world itself would eventually correct—or attract the Human Order Foundation, Chaldea, to intervene.
A major alteration would grow into a Lostbelt, pruned from Proper Human History by the world itself, becoming doomed remnants abandoned by the main timeline.
Could a Lostbelt escape its inevitable destruction? In theory, yes—if it was fortunate enough to acquire a Fantasy Tree and successfully counter-invade and overwrite Proper Human History.
Having witnessed the collapse of the Round Table and the death of the King of Knights at Camlann Hill countless times, Guinevere finally understood the Church's scheme.
They knew fate could be changed, but they also knew the consequences. They wanted her to see this harsh reality for herself, hoping she would willingly accept her destiny.
"Otherwise," she thought, "all these onlookers will become my enemies. And among them... Merlin is likely included.
"They won't allow the world to lose its future."
Lost in the unknown space, adrift among endless worldlines, Guinevere felt a profound sense of confusion. Even if she could defeat Merlin and the others, she would only turn this world into a Singularity or a Lostbelt.
And then, she would become an enemy of Proper Human History itself.
"If this is the only outcome of changing fate, then what's the point? To become a Lostbelt and spend a few more decades with Lia?"
Guinevere was supremely confident, but she had seen Chaldea's Chaotic Evil. She had also seen the ultimate malice the world itself would unleash if she tried to overwrite Proper Human History with a Lostbelt.
So, were these truly the only two choices? Either submit to fate and die, or struggle to turn the current worldline into a Lostbelt...
Still within the pure white expanse, Guinevere saw more.
For example, in the Fourth Holy Grail War of Fuyuki City—an event she remembered from her past life—after the man named Emiya Kiritsugu summoned her King of Knights...
...she saw his shock upon discovering that the King of Knights was, in fact, a girl.
In that instant, Guinevere finally realized it: there was another way to guide the world toward a good ending.
"History is like a young girl, dressed up by those who write it," she mused. "It doesn't allow the Annals of Time to stray onto divergent paths, but it does permit cosmetics and embellishments until the truth is unrecognizable, hidden beneath a veil of falsehood."