A Brand-New Combat Mode
"A Reality Marble? You said a Reality Marble! You possess a Reality Marble just like that great one? That person could summon the entire land of Egypt if they had enough magical energy…" A brown-skinned girl said in astonishment.
"No, my ability isn't anything that exaggerated," Shirou replied with a smile.
He turned to look at the girl and saw that she had beautiful long hair colored in alternating shades of blue and gold—strange, yet surprisingly fitting. She was adorned in golden ornaments and stood with a noble air.
"Insolent fool! How dare you interrupt while I'm speaking! Do you not realize you're speaking to the great Pharaoh Nitocris?! Lower your head! Show some proper respect!" The girl struck her golden staff on the ground and shouted with mock severity.
"Uh… sorry," Shirou apologized obediently.
Even though the Heroic Spirit before him looked and acted more like a sulking neighborhood girl than an actual queen, and was not intimidating in the slightest, Shirou decided to apologize earnestly.
"Hmph, as long as you understand your error. Since you are a guest, I shall graciously allow you to gaze upon the glorious figure of this great Pharaoh. Raise your head when you speak." Satisfied with her perceived authority, Nitocris's gaze softened as she looked at the boy. "Now, let me tell you about the magnificent deeds of the Pharaoh of Pharaohs—Ozymandias!"
Just as Nitocris was about to launch into a lengthy speech, Da Vinci stepped forward and interrupted.
"Alright, alright, let's save the history lesson for later. Let's focus first on the remodeling plan."
"Yes, if we're going to do this, just having a Reality Marble isn't enough. If you want to become stronger… right! Why don't you use your Mystic Eyes to reinforce your entire body from head to toe?" At that moment, a woman in a long black sorceress robe suggested.
"I agree with Medea's assessment," Da Vinci nodded.
"Sounds fun. Let's go with that," Cú Chulainn chimed in approvingly.
"Medea!" Seeing the blue-haired, pointy-eared woman step forward, Shirou cried out in surprise. Even the infamous witch of betrayal was here now?
Medea looked at him with a smile and said, "Oh my, looks like you've got memories of meeting me, huh? But which world would that have been in, I wonder? Hehehe."
"I'm starting to feel more and more confused about what's going on here…"
Shirou mumbled to himself, now having seen not only the infamous black witch known for slaughtering hundreds of children but also the traitorous Medea. He couldn't help but feel a little uneasy.
"Well, Heroic Spirits as a system are already full of mysteries. Even I don't know everything, so don't worry about it," Da Vinci comforted him.
Eventually, with the help of various geniuses and magi from the Age of Gods, a complete plan was formed for modifying Shirou's spiritual foundation.
Using the Holy Grail, they created a special Spirit Origin that would evolve and grow stronger in sync with his inner self.
Shirou used the Holy Grail to develop a unique Spirit Origin just for himself—essentially turning his inner Reality Marble into a "phantasmic spirit" that normally remained dormant.
When needed, Shirou could use the FGO system to connect with Chaldea and summon this Spirit Origin as a Heroic Spirit to possess himself.
In doing so, he could manifest his ideal self and temporarily transform into an ideal Heroic Spirit.
Such a feat should've been impossible. But thanks to the Holy Grail—the almighty wish-granting machine—this miracle was realized. Just like with his projection magecraft, the more complete and powerful his imagined self became, the stronger his Spirit Origin would grow.
Empowered by the Holy Grail's vast magical energy, the boy's Mystic Eyes connected to the past, present, and future—reaching into parallel worlds, alternate timelines, and Lostbelt universes in search of the so-called "strongest version" of himself.
In those different worlds, there existed entities that closely resembled him—perhaps his past lives, future selves, or parallel counterparts:
A white-haired archer in a kyūdō uniform wielding mythic gear; A red-haired blacksmith who lived and died by the forge, mastering that domain to a godlike level; A man who endured endless time, achieving miracles beyond magic, reuniting with a beloved girl in a faraway utopia; A white-haired, white-robed Heroic Spirit who stood alone before the primordial goddess...
Which one of them is truly the strongest? At this moment, the boy didn't know the answer.
What he could pursue, for now, was simply to become the strongest version of himself he could currently be—nothing more, nothing less.
.
.
.
Later, Shirou had just stepped out of Da Vinci's workshop when he found several Heroic Spirits blatantly eavesdropping at the door.
"Hey, Shirou~ did you come looking for me to go on a date?" A lively fox-eared girl in a school uniform cheerfully rushed up to him.
"Ah… Ah! Suzuka Gozen." Hearing that familiar voice, Shirou froze for a moment before recognizing the girl before him. Unlike her fused appearance during possession summoning—when she had been combined with Yuigahama—this vibrant, dazzling form was her real identity.
"Shirou! You've finally accepted my invitation?" A tall and voluptuous woman in armor looked overjoyed, her eyes filled with emotion as she opened her arms wide and tried to embrace him.
This time, Shirou recognized her instantly and quickly stepped back, shouting, "Eh? Raikou! Wait! Don't come over here!"
"Eh? Why so cold? Did I do something wrong?" Minamoto no Raikou looked like she was about to cry.
"No, it's just… hugging like that would be bad in more ways than one," Shirou said, frantically waving his hands.
"..." Standing silently nearby was Ushiwakamaru, watching the boy who once patted her head like an older brother would.
"Brother? So you really are Big Brother?" "An alternate-world brother! You're just like the one from back home!"
At that moment, Shirou noticed two identical little girls looking up at him with wide eyes—one with silver hair and fair skin, the other with darker skin and a different hair color.
"Ilya?! Two Ilyas?!" Shirou exclaimed in shock. The silver-haired girl was dressed like a pink magical girl, complete with a floating five-pointed star-shaped ring.
The other wore red and black—her outfit looked oddly familiar... and a bit too revealing.
"I'm Chloe~ Nice to meet you, Onii-chan~!" The darker-skinned girl winked and smiled at him.
"Yaaay~! I never thought I'd meet Shirou here too. Ilya's so happy! Now I've got three brothers! It's basically a harem~!" Ruby flapped her wings and twisted in the air gleefully.
Ilya stood frozen on the spot. She looked like her heart skipped a beat, but then her face turned red as she shouted in embarrassment, "Ruby! Shut up already!"
Blushing, she turned toward the boy and introduced herself: "Big brother, hello. I'm Illyasviel."
"Want to sit somewhere and talk?" Shirou looked at the two girls. Judging from their behavior, they weren't the Ilya he knew. Smiling, he suggested a chat.
"Sure!" Ilya and Chloe both nodded.
After that, Shirou sat down with the two girls and talked about their world. To his surprise, in their timeline, Kiritsugu had ended the Holy Grail War, and Ilya had gone on to live a normal life—but was later dragged into another series of events.
"So there's a world like that, huh…"
Shirou sighed. Instead of being a vessel for the Holy Grail, the girl lived as a ten-year-old magical girl, collecting Class Cards and fighting to save her precious friends.
"I was also pretty shocked when I saw a black-haired Onii-chan," Ilya said with a smile.
"Mhm. Ilya, Chloe, you've both worked so hard. You're amazing," Shirou said as he patted both girls' heads, praising them gently. He sincerely hoped their efforts would be rewarded with happiness.
"Hehehe~ Big brother praised me!" Ilya squinted her eyes in delight.
"Geez… don't treat me like a little kid…" Chloe's face turned red as she mumbled quietly.
"Well then! Where's the kitchen? Let me treat you two to something special today!" Shirou rolled up his sleeves, full of enthusiasm.
"Really?! I'll help! My Onii-chan's cooking at home is super tasty!" Ilya said joyfully.
"You're good at cooking too, Big Brother? I wonder if you're better than the one at home. If you don't satisfy me… I'll demand compensation~" Chloe said with a mischievous grin.
"Haha, I've never compared, so who knows?"
Shirou chuckled and shook his head. He was just someone who had lived two lives—wandering across most of the world in his previous one and picking up lots of experience along the way.
And so, amid Chaldea's rising expectations, Shirou took charge of all the meals for the day—bringing tears of joy to the entire staff. Finally, amidst heartfelt farewells, they watched him return to his own world.