A magic circle was drawn on the floor of the dojo, courtesy of Kiritsugu. Shirou watched with fascination from the side.
"There, now go sit in the middle, Shirou," Kiritsugu instructed.
Shirou nodded and quickly followed his father's instructions. Kiritsugu sat behind Shirou and placed his hand on Shirou's back.
"Now listen closely. It's going to hurt, so prepare yourself, Shirou. This ritual will use my own energy to kickstart your Magic Circuits, you will feel something entering your body. Let me know when you're ready."
Shirou took a deep breath. "...I'm ready, Dad."
"Okay, then one, two... three!"
On the count of three, Kiritsugu activated his own Magic Circuits and directed his Od directly into Shirou's body. Instantly, Shirou felt pain coursing through him. It felt as if something was slowly crawling inside his body. The crawling sensation then transformed into intense heat, threatening to burn him from the inside out.
The ritual took some time, but eventually, Shirou's Magic Circuits activated. Kiritsugu ceased the flow of Od and caught Shirou as his body started to fall. Shirou's body felt overheated, but gradually, the heat dissipated until it disappeared completely. Kiritsugu with a knowing looks smiled a little, relieved.
'I wish I could apologize to you, Saber,' Kiritsugu thought, his mind filled with regret as he gently laid Shirou's body down.
Truth be told, Kiritsugu wasn't particularly confident in his ability to perform this ritual. After all, he was considered a third-rate magus at best. He had done it once before, but Maiya was an adult, whereas Shirou was just a child. Fortunately, the artifact he had placed inside his son was a potent Noble Phantasm, which provided the holder with a passive healing effect even without its original owner.
Observing Shirou's current condition, it seemed like he would need to wait a while before receiving an answer from Shirou.
"Hm? Are you going to let him just sleep on the floor? That's a no-no, Kiri."
Kiritsugu was startled. Someone other than him and Shirou was present in the dojo. Someone that appeared out of thin air, as none of the alarms he had set on the bounded field around the house were triggered. Someone who had a very familiar voice.
Kiritsugu turned and saw her—dressed in a simple, long white dress, her long hair gently swaying. Her ruby red eyes gazed directly at him, and her face displayed a deep longing.
Kiritsugu composed himself enough to mutter a word. "Iri..."
The woman, whom Kiritsugu called Iri, smiled. "I'm back, Kiri."
"How?" Irisviel von Einzbern, or Iri as Kiritsugu lovingly called her, walked closer and made a shushing gesture.
"Let's move our son to his room first; we can talk after that," she said softly.
Kiritsugu could only nod weakly in response. After they had brought Shirou to his room, Kiritsugu and Irisviel sat in the living room. Kiritsugu still wore a deeply confused expression, while Irisviel let out a small giggle of amusement.
"Let me ask once again, how? I-I thought you were..." Kiritsugu trailed off.
"Gone? Died? Turned into a golden cup?" Irisviel grinned.
"Iri..."
"Okay, okay, sheesh. You need to lighten up a bit, Kiri," Irisviel said playfully. Her expression then turned more serious. "To be honest, yes, I was gone, Kiri. You were there. It's not a trick or illusion; I was actually going to fulfill my role as the Lesser Grail."
Kiritsugu winced at the memory.
"You know, Kiri, at that moment, I truly thought that would be the end of it. But something went wrong, so much wrong, and you know what I'm talking about, right? You were there, after all."
Kiritsugu tightened his fists, his voice quavering slightly. "...The grail was corrupted."
Irisviel nodded. "Yes, by an evil god no less. Angra Mainyu. I know more or less why Angra Mainyu was there, but the important thing is that many of the grail's built-in systems suffered fatal errors, causing it to diverge."
She continued, "We should have known after someone like Caster was summoned. It should have been obvious that a supposed artifact that can only summon heroes was able to summon someone so despicable. Then came the worst part of the corruption..."
"The sick monkey paw wish granting," Kiritsugu interjected.
"...It shouldn't work like that, yet Angra Mainyu managed to corrupt it," Irisviel said.
The two of them fell into silence for a moment before Kiritsugu asked, "Then, how can you... be here?"
Irisviel smiled. "You can thank our son for that."
"Shirou?"
"As the grail was corrupted, it somehow found a sliver of connection between itself and Shirou. Then, with some of its last proper systems still functioning, it took a gamble. It granted Shirou his wish."
Kiritsugu now felt very puzzled. "That's not-"
"Possible, under normal circumstances, yes. But the grail, disregarding its own rules, as a last resort, decided to grant him one, despite our son not even participating in the war."
"But how about the corrupted wish?"
Irisviel gave Kiritsugu a reassuring smile. "No, this one wasn't corrupted. It's a genuine wish, brought to reality by the last working, uncorrupted system of the grail."
Kiritsugu let out a silent sigh of relief. "Then, what's his wish?"
An amused look appeared on Irisviel's face. "To meet a hero and to be a hero."
"T-That's..."
"Just like his dad," Irisviel teased.
For a moment, Kiritsugu's eyes lost their light. "Iri, you should know that..."
"I know, Kiri. But we are here. We will guide him."
Kiritsugu could only stare at his wife in silence.
"Shirou's wish was granted, but it came at a cost"
A concerned look returned to Kiritsugu's face "...What's the cost?"
"For Shirou to purify the grail from Angra Mainyu and dismantle the grail at any cost."
Kiritsugu had already contemplated planting explosives to disrupt the local leylines and the grail inner workings. But dismantling the grail? He wondered if that was even possible.
Seemingly aware of her husband's thoughts, Irisviel then explained, "Normally, at least one of the three founding families are needed to dismantle the grail properly. But the last act of the proper grail caused some changes."
Irisviel raised her hand and continued, "First, unlike before, the grail is now fully under Angra Mainyu's control. Second, the privileges that the three founding families had were revoked, meaning they couldn't monitor or tweak it anymore. Third, the corrupted grail no longer has most of the limitations placed on the proper grail. It's possible for the current grail to choose as many masters and servants as it likes or even summon its own servants without needing any masters." Irisviel paused for a moment.
"I wouldn't be surprised if there soon will be an all-out servants summoning on a scale unseen before. To make things worse, Angra Mainyu still hold the remnants of the wish-granting system. Sure it's now broken apart, but given enough time and Angra mainyu will undoubtedly fix that system."
Silence settled between them once more. This grim situation was on a whole different level for Kiritsugu, far beyond his participation in the Fourth Holy Grail War.
"Then..." Kiritsugu broke the silence. "...What's Shirou's part in all of this?"
"To answer that, Kiri, could you tell me how many Magic Circuits our Shirou has?"
Kiritsugu closed his eyes for a moment before answering his wife, "38,862,602,496 circuits, all of high quality."
Irisviel chuckled. "Impressive, right?"
Impressive, she said. Kiritsugu scoffed. It was inconceivable. No human should have this many Magic Circuits. He had even entertained the thought that Shirou might not be fully human.
"You see, Kiri, to grant our Shirou's wish, the grail gave him two gifts. First, as you already know, it gave Shirou an absurd number of high-quality circuits. There's a reason for that. Without them, our Shirou wouldn't be able to handle the second gift."
"And what is the second gift?" Kiritsugu asked, his voice filled with anxiety.
"A direct access to the Throne of Heroes, the grail made a pathway between the Throne of Heroes and Shirou's soul" Irisviel dropped the bombshell.
"W-What?!"
Irisviel chuckled at Kiritsugu's reaction. "The grail turned Shirou into a kind of pseudo-grail. He has the ability to summon and maintain numerous servants alone, but without the grail's wish-granting system. All of this was done to prepare him to face the corrupted Angra Mainyu grail. Shirou, our son, is the chosen champion and our only hope against Angra Mainyu."
Never in Kiritsugu's wildest dreams could he have imagined being alive to hear this. His son, whom he had saved from his own failures, was fated to fight against the very same abomination that had caused their tragedy.
A pseudo-grail in the form of a human against a corrupted grail controlled by a demon god. The stakes were higher than ever before.