There was one particular friendship I always wished canon would have explored. So let's see if I can make it canon here.
An Unusual Pair
"Your highness."
"Sumeragi-
san."
Nunnally could not help but be curious about the newest lady in her brother's personal orbit. Well, as much as one could call it that. They only had a business relationship at this point in time, although much could change in the five years Sumeragi Kaguya would stay with them.
The Japanese girl spoke first, a pleasant smile offered by the one of lesser station. "How may I serve you, your highness?"
Her Britannian was quite good, the barest hint of an accent telling Nunnally that this young woman had learned the language since she was a little girl but not since she could speak. Truly though, she could not say for sure what drew her to seek out the Sumeragi heiress. Perhaps that she was new and unusual, maybe idle curiousity about her aims regarding Lelouch. Maybe even the fact she was already beautiful at fourteen and Nunnally could not help but be a little smitten.
Ultimately though, she knew none of that was the main reason. "Do you have some time to join me for tea, Sumeragi-
san? I am usually surrounded by men and women my senior, so I would like to speak to someone my age for once."
She suppressed a grimace; that was a bit more direct than she should have been, but now the words were already out. At least the fact she spoke in Sumeragi's native Japanese instead of Britannian distracted the other girl somewhat from the bluntness. Nunnally, too, knew to converse in several languages.
After a moment of well-hidden surprise, the other girl beamed at her and curtsied. "My, of course. I would be delighted." A polite agreement, though with a hint of actual interest there. Nunnally may be bad at being courteous, but she could still read a social situation well enough.
Not much later, the two of them were facing each other on an otherwise empty terrace, a single table with two chairs and refreshments brought by the help. Nunnally waited until everything was set up as was customary, waited until their cups were filled, and was promptly overtaken by her de-facto guest. "If I may say so, your Japanese is quite good. Did you and your brother learn together?"
She just shook her head and huffed. "His interest in languages is a recent matter while I have been learning several for a few years. He is far more talented at it than I am." Then, with a wink to her guest, she switched to Mandarin. "Although I inherited our mother's talent at arms in turn."
The silence held for a moment while the Japanese girl took a sip from her tea, eyes closed. Once the cup was lowered however, Nunnally could see what had to be a carbon-copy of her own impish grin. "I'm afraid I have yet to hear of such," she answered in perfect Mandarin, "although I am certain I soon will. Considering our age, greatness lies ahead of us both." Nunnally knew her brother was planning to lease his combat forces this year, so she raised her cup in response to sip from her own tea. It would be sooner than Sumeragi might think.
Then she grimaced as her guest turned the tables and switched to another language; one she did not learn. After a moment of expectant silence, Nunnally sighed softly and reached for the tray of pastries. "I am afraid you caught me. I do not speak Arabic. What were you saying?"
While she began to nibble on her treat, Sumeragi nodded and ran a finger over the rim of her cup. "I see," she offered in Britannian once more, "I was saying that I look forward to hearing of your exploits, your highness." And as if to poke a hornet's nest, the girl switched to Japanese to add "You can't catch them all" with a renewed grin.
Nunnally raised one immaculate eyebrow and responded: "Quite true. You will hear many great things from me in the future."
The reaction she got was a barely suppressed groan while Sumeragi quickly picked up a cookie to munch on. "Gah, German. I knew I should have studied that!" Now it was for Nunnally to grin, then giggle. Sumeragi followed moments later and the two took a moment to bask in their shared mirth.
"I have to admit," Nunnally noted while her guest enjoyed the baked goods, "this is much different to what I am used to. Tea parties with the nobility are always so stiff and formal. This is better, Sumeragi-
san."
"I concur."
Both of them took a short while to empty their cups and have them refilled, then the Japanese girl continued. "And please, Kaguya will suffice, your highness." Nunnally could not help but blink at her a few times; the Japanese were well-known not to allow use of their first name so easily.
In the end, she just accepted it and returned the notion: "Nunnally for you, then." After a moment however, she decided to be coy. "
Kaguya."
As expected, she received a raised eyebrow in turn and the other girl folded her hands with a grin. "My, at least add a -
chan, we aren't that close."
"Are you sure,
Kaguya?" A twitch of her eyebrow and Nunnally could not help but giggle at the sight. She would be in for one hell of a chastisement if she did this at an official function, but right here, right now? She found it fun, but decided not to push any further. "Hehe, alright, alright. I won't do it again, Kaguya-
chan."
The narrow-eyed gaze she received prompted another giggle, then the other girl carefully picked up another cookie... and promptly threw it at her. Nunnally was too surprised to catch it and the thing broke to pieces on her forehead, raining crumbs onto the dress she wore on base and what little cleavage she had. It was her turn to stare at the Japanese girl, who leaned back and looked at her nails. "We're even now."
Silence passed as the two of them stared at each other. A Japanese addressed without any honorific without permission, and a princess full of crumbs from a ballistic cookie.
Nunnally broke the silence: "My tutor would hunt me to the other end of the world with his cane if he ever found out about this."
Kaguya nodded sagely. "My father would give me the first spanking I ever got in my life if he knew."
A moment later, both girls broke into laughter. Not polite giggles, but proper laughter. It felt good, Nunnally thought, to laugh freely. She could only do that around her mother, her brother, and Milly. She felt content, sitting at this table, laughing together with a girl she hardly knew but felt she wanted to know better.
After a time passed and the two of them calmed down again, Kaguya leaned back with a smile. "Ah, that felt good. I never expected things to end like this. At first I thought you wanted to snatch an ally from your brother's grasp."
Nunnally's mirth was dampened by the admission and she frowned lightly, but shook it off before also shaking her head. "No, no. Lelouch is much better at politics than I am. I'm not made for life at court and I'd prefer if I never have to spend too much time there." She spoke from the heart, feeling that while admitting such a matter could be disastrous if the wrong ears heard them, she knew this island was remote and free of such ears. "I rather follow in my mother's footsteps."
Kaguya raised her cup at that, as if to toast her. "Ah, a second coming of the Flash, that would truly be a sight to see." The princess raised her own cup in response and the two drank properly instead of just sipping. The warm liquid ran down Nunnally's throat, a familiar bitterness. Once she was done, Kaguya continued with a smile: "But either way, it is always good to have friends in high places."
"Indeed." Nunnally took and raised another cookie in response, a gesture that was soon imitated by her guest. "Although I was thinking, perhaps we could ignore the high places while in private?"
She became nervous now, wondering whether that might be asking for too much. Commoners had friends; nobles and royals had allies. Yet she kept wondering what it would be like, to have a friend all her own. Milly might be called Lelouch's friend, but even those two did not spend as much time with each other as they used to; Nunnally talked with her even less.
Kaguya mulled over her proposal, having caught the princess' intent. It took a few agonising seconds of her staring at the cookie in her hand before the Japanese girl pushed a stray strand of ebony hair aside. "I appreciate not having to speak with a forked tongue today, but we hardly know each other." Read, no. "Though we will likely see each other quite a bit over the next few years. There is much time to get acquainted."
Once more she had been had, surprised by the turnaround. Nunnally smiled and nodded, then she ate her final cookie for the day. "Very well, how about we start now? What are your hobbies, Kaguya-
chan?"
"Hm...."
The heiress tapped her chin a few times as she considered Nunnally, then she shrugged. "My mother tried to get me into flower arrangement, but I do not have a good feeling for that. With what little free time I have, I usually try to pick activities neither Mother nor Father would approve of if they knew, but nothing that others can notice easily."
"Oh? Like what?"
"Like... the last month before coming here, I had one of my maids bring in some super naughty manga to read before bed."
"Um, pardon, manga?"
"Something like comics."
"Ahh!"
Nunnally giggled as everything clicked into place and she could not help but grin at her potential friend. "Be sure to pass them on some time, you got me curious."
"Can do, you will be my partner in crime." They both chuckled and Kaguya pointed back at Nunnally. "Now, out with your dirty laundry. What's with your hobbies?"
Now it was for Nunnally to think. "Well, I actually tried my hand at arranging flowers, too. My teacher did praise me, but I never felt that it was for me. It is too calm, too... slow, if that makes sense. I used to sneak down to the garage and watch Knightmare maintenance, or I went to the shooting range."
Kaguya nodded a few times, a thoughtful glance going to Nunnally. "I imagine you were scolded a lot." Though the princess shook her head at that.
"Not overly much, really. My brother and sister Euphemia got really worried, but Mother just laughed and said I got it from her. At some point she just told me to take an escort instead of sneaking out."
"Your mother sounds great. I hope I can meet her one day."
Nunnally made an agreeing noise and smiled. "I think she would like you quite a bit. You are both a lot more forward than the snakes at court."
"Be sure to introduce me one day." Kaguya reached for another cookie while Nunnally folded her hands, already sated, but then the Japanese girl hesitated. "Say, there was something I always wanted to try. Though it might get us in trouble."
She received an intrigued look at first, though Nunnally soon frowned softly. "Nothing that would strain your injuries, I hope?"
"Oh, that?" The other girl shook her head in turn and finished off her final treat for the day. "Not to worry, Nunnally. It has been a few months, I am all healed up. So, are you interested?"
Soon after, the pair of them wore matching grins once more.
//// Scene ////
Two hours later, a duo of giggling girls stumbled back into the main base. Right toward an exasperated Jeanne who had her arms crossed and brows furrowed. "Your highness, Sumeragi-
sama, if you were so kind as to explain this?"
"This what?" Nunnally asked her while steadying the wheezing Japanese. Jeanne merely held up a black-and-white picture of the two of them, barely more than a blur. "The fact I know you possess no license aside, you broke the speed limit. I do not even know how you broke it by that much."
Kaguya finally gathered herself and stood properly again, voice hoarse from how much she had been whooping on their excursion. "That, Dame Rowe, is simple," she explained sagely. "Bikes are awesome." And as if on cue, both girls broke into giggles again.
Jeanne merely covered her face with one hand and wondered if her Prince could run herd on those girls.
Notes: I do not even know if it is canon, but I read some submaterial that covered these two knowing each other; it makes sense too, seeing that Kaguya should have been around the shrine where the siblings lived before the invasion.
Even with their adjusted personalities, I think they still play off each other quite well. This scene would be playing somewhere during Year 6, probably around May or June, a few months before Kaguya's fifteenth birthday.