As a seasoned Type-Moon fan and a devoted follower of The Case Files of Lord El-Melloi II, how could Shinji not recognize Gray? He knew Gray even better than Waver, who had only recently taken her in. His previous actions were deliberately done to show Waver that Gray's identity was complex and that she harbored significant secrets.
This secret hadn't been unraveled before Shinji crossed over, but that didn't stop him from making such a decision. Because she was a descendant of Artoria and had a similar constitution, modern methods of teaching were unsuitable for her. Only someone like Zelretch or someone with similarly unique qualities like Shinji could truly unlock her potential.
Waver didn't immediately agree or refuse but asked, "What can you teach her?"
"This."
A surge of magical energy erupted from Shinji, transforming into a gust of wind that blew Waver's long hair into disarray.
"And this."
Shinji mimed holding and wielding a greatsword.
"She doesn't use a sword," Waver said.
"Then what does she use?"
"Many things. Her weapon is quite special; it can change into various forms. I've seen it become a scythe and a large shield."
"How convenient, I know how to use those too," Shinji continued his demonstration.
Waver, despite not being versed in martial arts, could see through his Discerning Eyes the professionalism behind Shinji's movements.
"You are a monster."
"Thank you for the compliment. I'll continue to do my best. Unlike magic, martial skills emphasize teaching through example rather than explanation. Believe me, Waver, there is no one more suitable in this world to teach martial arts than me."
Knowing Shinji was telling the truth, Waver hesitated no longer.
"I can entrust Gray to you for a while, but I have three conditions."
"Name them."
"First, you must ensure Gray's safety."
"Of course."
"Second, Gray must not leave my sight for too long. She is my apprentice, and I must take care of her."
"No problem."
"Lastly, both Gray and her guardian must agree."
"Alright, I agree."
...
"What? Let this guy be Gray's martial arts instructor? I don't agree!!!"
A lively male voice interjected. This was the guardian Waver had mentioned, though Shinji hadn't seen the person, only heard the voice.
Upon informing Gray of Shinji's proposal, this voice quickly spoke up, even faster than Gray's response.
"Why?"
Shinji wasn't angry; he looked at the source of the voice with interest—Gray's right hand.
"You look like a bad guy, and you have an aura of malicious danger, even more annoying than that prematurely aging teacher."
Tsk, such a sharp tongue, hitting two targets at once.
"Hey, incompetent teacher, have you given up and resorted to self-destruction?"
The voice became more and more excessive, and Waver finally couldn't stand it any longer.
"Gray, could you please hand Add over?"
"Sure."
Hearing Gray's response, the voice immediately became panicked.
"W-Wait a minute, Gray! Are you betraying me?"
Gray ignored his protest and shook her right hand.
With a crisp sound, the fixture came off.
From within the dark cloak rolled out a long cage that resembled a birdcage.
Inside the cage was a box composed of several pieces, resembling a Rubik's cube. However, this box was far more intricate and complex, exaggeratedly engraved with eyes and a mouth.
As soon as it fell to the ground, the eyes opened wide, and the mouth kept moving nonstop. The voice they heard earlier came from this mouth. He, or rather it, was named Add.
"You, you jerk! We've lived together for over ten years, I thought we were friends! You know I don't have many friends, and now you should at least hesitate a bit out of decency before betraying me! Wait, there's still time, quickly reconsider and hide me away, please! I'm begging you!"
The cage began to tremble as if shivering continuously, clearly showing his fear of Waver.
Waver ignored Add's pleas, grabbed the top of the cage abruptly, and shook it like a cocktail shaker.
"Aaaaaaahhhhhh!"
Add continuously banged against the cage, crying out in agony.
As the eyes on the cubic box spun, Waver seemed to think it had learned its lesson and threw it back to Gray, but Shinji intercepted it midway.
"Let's have a chat, Add."
"There's nothing to talk about between us. No matter what you say or do, I won't agree."
"Acting tough after being so scared earlier," Shinji said with a smile.
"I've always been tough."
"Is that so? As expected from someone in the legend of King Arthur..."
Mid-sentence, Shinji stopped speaking and silently mouthed a few words.
"You, you, you, you you you you—!"
Add's tone instantly changed, becoming even more panicked than when he was begging earlier.
"What about me?"
Shinji wore a confident smile.
"How much do you know?"
"Not much, I'm not clear about Gray's situation, but I know a bit about you—something about a weapon, a tower, and faraway lands."
"Who exactly are you?"
"Who I am isn't important; what's important is my connection to her..."
An ancient aura emanated from Shinji, making Add's eyes widen to the extreme.
"Th-This is!!!"
"So, still opposed?"
"Enough, I agree to let you be Gray's instructor, but I still don't like you."
"Understandable, an overprotective brother would always feel uneasy seeing another guy near his sister. Don't worry, I won't take up too much of Gray's time. I'll just teach her some basics; she'll have to explore and develop the deeper aspects herself. Now, Gray, are you willing to accept my guidance? I may not be as good a teacher as Waver, but I've been trained by several masters and am confident I'm better than most lecturers at the Clock Tower."
Shinji handed Add back to Gray with a smile. Gray accepted with both hands, her gray-green eyes looking nervously at Shinji.
"Um, can I ask a few questions?"
"Go ahead."
"Add is—"
"Ask him his secrets yourself. If he doesn't want to tell, I can't say much."
"Then, the 'her' you mentioned earlier, is she King Arthur?"
"Yes, King Arthur, Artoria Pendragon, likely your ancestor."
Shinji didn't hide the truth.
"Do I resemble her a lot?"
Gray's voice trembled inexplicably.
"Very much so, almost identical except for your hair color."
"I see."
Hearing this, Gray's voice became increasingly downcast.