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"You're saying you're my father? Impossible!"
After listening to Zuke's explanation of their relationship, Illyasviel—now in her "Sitonai" form—immediately rejected the claim without hesitation.
In her heart, the only parent she had ever known was her mother, Irisviel. The concept of a "father" simply didn't exist in her memories.
That role should have been filled by Kiritsugu Emiya. But in the Fate/Zero mission world Zuke had entered, Kiritsugu and Irisviel's relationship had been more like... a partnership of convenience.
Their connection had never gone beyond ideological alignment—Irisviel had approved of Kiritsugu's twisted sense of "justice," which was why she had willingly pretended to be Saber's Master.
As far as Illyasviel was concerned, Kiritsugu was just a playmate who had spent some time with her in the Einzbern Castle. Nothing more.
And thanks to the Einzbern family's relentless indoctrination—"That failure Kiritsugu ruined everything!"—her opinion of him had only soured further.
"It's normal that you wouldn't understand. To put it simply, your mother—Irisviel—is currently living happily with me in another world."
Zuke sat on the couch opposite Illyasviel, smiling as he explained the origins of their connection.
"Given that, wouldn't you say I qualify as your father?"
"With... Mom? In another world...?"
Illyasviel froze. The idea had never crossed her mind.
In her understanding, souls were supposed to dissipate after death. Only those who had achieved great deeds in life—Heroic Spirits—could be recorded by the Counter Force and enshrined in the Throne of Heroes.
And she knew full well that her mother, Irisviel, had been nothing more than an ordinary homunculus. There was no way her deeds could have earned her a place among the Throne's legends.
So... what was this "other world" Zuke was talking about?
"Not only that, but in that world, I even summoned a parallel version of you as a Servant."
Zuke continued, knowing full well that his words would have an effect—because despite her current form as "Shidounai," this was still Illyasviel at her core.
"And she called me 'Dad' right away."
The Illyasviel from Prisma Illya's world had accepted him as her father almost immediately, even if her understanding of the relationship came from the Holy Grail System's implanted knowledge.
When Zuke had mentioned this to Irisviel, she had explained it simply: "Illya has always lacked a father's love. She must have yearned for one deep down."
So when Zuke had filled that role, she had latched onto him almost instinctively, growing attached in no time.
And if the Prisma Illya version of her was like that... then this Illyasviel—Sitonai—must have the same longing.
"P-Parallel world...?"
Illyasviel was stunned. If this was about parallel worlds, then it did make sense.
The Einzberns were a magus family, after all. Illya had studied the concept of parallel worlds in her lessons—mostly because the Second Magic was the "Operation of Parallel Worlds" itself.
Hearing that Irisviel was alive in another world... part of her wanted to believe it.
Because she desperately wished Irisviel were still alive.
But in this world, her mother had definitely become the Lesser Grail during the Fourth Holy Grail War. There was no bringing her back.
So if Irisviel could be alive in another world... she was willing to accept that.
And yet, a small, bitter jealousy flickered in her heart—
Why does that other Illya get to live happily with her parents in a peaceful world... while I have to suffer like this?
"Illya! Don't just believe him!"
Just as Illyasviel was leaning toward accepting Zuke's words, Sella—still bound nearby—suddenly shouted.
Illyasviel's mind was still that of a child, shaped by the Einzbern's sheltered upbringing. She was naive enough to be swayed by Zuke's story.
But Sella, as Illyasviel's homunculus maid, had received far more rigorous education—enough to recognize when something sounded too good to be true.
To her, Zuke's words sounded like a scam—tailor-made to manipulate a lonely little girl.
"I get why you don't trust me. But I've actually been thinking... there might be a way for you to see Irisviel again."
Zuke wasn't bothered by Sella's skepticism. If he were in her position, he wouldn't believe a stranger's claims either.
But he wasn't just spinning a fairy tale. He had considered how to make it happen.
And the method... was simple.
"Ionioi Hetairoi."
He turned back to Illyasviel, his tone so suspiciously cheerful that even Sella and Leysritt felt like they were witnessing a child predator at work:
"Sitonai, if you acknowledge me as your Master... I might just be able to arrange a reunion with Irisviel. What do you say? Want to give it a shot? You're in an unmastered state right now, aren't you?"
Sitonai's current form was closer to a Pseudo-Servant—while she was anchored to Illyasviel's body (which could have been a Master), she was technically a Masterless Servant.
Which meant... she could accept Zuke as her Master.
"Wait, you're a Servant! How can a Servant even be a Master?!"
Sella couldn't help but interject. The idea of a Servant contracting another Servant made no sense to her.
"Who said Servants can't be Masters? The Holy Grail War's rules don't forbid it."
Zuke grinned.
The Holy Grail War's system was full of loopholes—which was why the Einzberns kept trying to exploit them every time.
The Third War had given birth to Angra Mainyu.
And now, in this War, they had created an anomaly like Sitonai.
As for whether a Servant could be a Master...
Just look at Medea from the original timeline.
She had broken the rules by summoning Assassin as Caster.
So if she could do it... Zuke becoming Sitonai's Master was absolutely possible.
"..."
Illyasviel had to admit... she was tempted.
She desperately wanted to see Irisviel again.
But if she formed a contract with Zuke, making him her Master...
...That would mean he'd gain Command Spells over her.
To be continued…