Mayhaps

"Why hello Shirou Emiya. How are you doing this fine night? So where is your Servant? Are they lost?" The little white-haired girl said mockingly.

"Shirou, do you know her as well?"

"No- I don't know her." You said almost saying Oda's name.

"Let me introduce myself, I'm Illyasviel von Einzbern, but my family calls me Tiny **** Machine, and unlike you, I have my Servant with me, she's Berserker. Now-" Illyasviel couldn't finish her sentence before Berserker spoke.

"No Miss Einzbern, I refuse to kill a Master who can't even use his Servant. Let him meet the Overseer so he can get things sorted. Should we guide them to him Miss Einzbern?" But before Illyasviel can respond Oda interrupted.

"Just direct us to him and we'll get on our merry way."

"You know what? How about we bring you there?" Illyasviel questioned back.

You and Oda looked at each other and pondered what to do. Oda almost seemed to wait for your answer, so you do.

"Sure why not, at the same time you can teach me a bit about... well all of this. Maybe even some magecraft later on." You said responding to Illyasviel, a bit excited somehow?

Rin Tosaka POV

"So that interaction with Emiya went well," Archer told her sarcastically.

"Yeah. NO SHIT ARCHER! So he's also a Master, not only that, he has the fucking Saber Servant. Also, how did you know it was a Saber Servant?" She questioned him.

"Premonition I guess?" He responded half-assly. "Anyway, that Servant is quite powerful. I believe that you should take care of him tomorrow at school."

"Good thinking. Normally he shouldn't have his Servant with him unless he planned to kill everyone. And we don't know what her True Name is. I'll get rid of him as soon as I can." She responded confidently.

Shirou's POV at the church.

"Well, the Overseer is stationed here. I'll stand outside the gate, good luck. Hope you can get something arranged." Illyasviel said happily before you entered the gate. "We are going to stay out."

As you entered the Church past the gate, you saw two characters, both were praying and turned to look at you. The one that looks surprised seeing you, had long braided blond hair and a school uniform. She looked... familiar.

But someone interrupted your train of thought. The person who you assumed to be the Overseer spoke up. Who looked like a buff Christian Night Priest, hopefully, he doesn't follow the stereotype.

"Why have you come here?"

Oda looks at me, nods, and starts speaking. "I'm sorry to bother you on this first night of the Holy Grail War, but our Servant has gone Rogue, Shirou tried to stop her with a Command Seal, but she resisted it, I'm afraid we won't be to participate anymore." Understanding what Oda is trying to insinuate you continue by saying. "Would there be a way to get a replacement Servant for the time being? Or maybe even replenish my Command Seal?"

"I could do you both of those things, bring your first to mine so I can transfer you a Command Seal." So you do so and you see the symbol on your hand reappear. "Now as for the replacement Servant. Lancer, please come here."

The beautiful high school girl got up and tried to object. "But Kotomine!" "Do as I ask, or do you want me to Command Seal you again?" She didn't respond. She walked to me "I ask of you a simple pledge. For you to be just and kind. Is this a fine pledge, Master?" Her voice was angelic, as a Saintess spoke of her kindness.

"This is a fine pledge." As the both of us shook hands, I felt a wave of energy go through her, transforming her into her proper Servant form, but it also caused her to make a small yelp sound. "Are you ok Lancer?" You asked her. "Yes, I'm fine. It's just we are more compatible than Kotomine and I. So the surge of strength was something special." Compatibility? That's something new, so Servants are more compatible with one person than another? I guess it could be possible for Oda to actually betray me if she finds a more compatible Master... Then again...

You three walk out as you hear someone else moving toward the Overseer, but you are too far away to discern what he said apart from the words "You Mongrel!"

"So how was the meeting with the Overseer? It seems he gave you a Servant, what is her classification?" Illyasviel said as you walked out the gate. "I'm of the Lancer Classification, although I am quite weakened from my normal classification," Lancer said of her own volition, seemingly happy with her own freedom. "So what's your normal classification?" Berserker asked intrigued. "I was of the Ruler class last time I was summoned for a Holy Grail War. As the Overseer of the Great Holy Grail War." Berserker was surprised, but neither you nor Illyasviel knew what Berserker seemed so surprised about this 'Ruler' class. "But that doesn't matter anymore. I'm here, and here for Shirou as a Lancer Servant, but purer than in the Waxing Moon Ritual." She continued. "Wait, you too were in the Waxing Moon Ritual?" Berserker said looking even more surprised than before. "Well, now I want even less to fight you." "Well then Shirou, seems like our Servants made peace. So how about I walk you home? You can ask me questions on the way." Said Illyasviel in her usual happy-go-lucky tone.