A/N: I don't own the characters or the story, and this is a completely nonprofit fan work. This is simply a paraphrase to make the conversations flow more naturally into marriage and remove the focus in the S-support from them being siblings - and the same goes for all subsequent chapters and updates to this story. Credit to all the translators.
Corrin awoke with a start, her silken bedding twisted and in complete disarray. The sound of a sword swinging against training equipment outside had caused her to dream of the ferocity of war, of the battles she had endured and of those yet to come. She did not regret her decision to stay with her Nohrian siblings, but the idea of killing her own blood left a foul taste in her mouth. For the time being, she opted to push such bleak thoughts aside and investigate the noise.
Though Corrin wasn't sure about the time, she could see the moon was high overhead, and the sky was a deep midnight blue. She threw on her robe over her thin nightgown, neither of which did much to shield her body from the chill of the night. As she clambered down the ladder, the kiss of steel grew louder, and she could vaguely make out a tall, muscular silhouette practicing swordplay with one of the dummies.
"Xander?"
The Nohrian prince's movements were stiff, and his shoulders looked tense when he spun to see her, sword aimed in the direction of her voice. A look of surprise flashed across his face before he eased his muscles and sheathed his blade, muttering an apology. "Corrin? What is it?"
"It's very late. You're still training?" She eyed his heavy training armor and the wooden rack of dull, practice weapons - one of which was irreparably damaged.
Xander returned his focus to the wooden dummy, swinging his sword aggressively. "I don't have time for sleep. I have to...improve my skills for Nohr."
Corrin smiled sadly and sat criss-cross on the ground - a safe distance from Xander's training area. Chuckling to herself, she said, "You haven't changed one bit."
"What does that mean?"
"I was just thinking about back when I was imprisoned in the Nohr fortress, whenever you came to visit, you stayed up late to train, then, too." Corrin adopted a faraway look in her eyes, hugging her knees to her chest.
Pausing briefly, Xander glanced back at her from over his shoulder. "How did you know that?""
"I could see you training from my window, silly, and I could hear the metal." She chuckled, jumping to her feet and punching his shoulder playfully. He eyed her swing, neither expressing amused camaraderie nor offense. So serious - and strong as an ox. Her playful punch hurt her hand a little and hadn't made him budge in the slightest. Though he was shielded with his heavy armor and multiple layers of clothing, she imagined he was incredibly toned, but quickly pushed such thoughts away, a light blush creeping across her cheeks. Hopefully, the cloak of night masked her gaze - which had lingered a little too long. Corrin continued, "But I didn't want to lose, so I'd pick up my sword and train, as well. Sometimes pretend we were training together."
"Is that so..."
"Since we're both up now, do you want to train together for real?"
Xander held her hopeful gaze evenly, before sighing and cracking a light smile. He retrieved a dull, iron training sword from the practice weapon track to match his own - heavy and similar in function to an actual sword, but with the edges dulled enough to prevent deep cuts or major bodily harm. Slowly, he stepped towards her and placed the sword in her hands, spreading her fingers across the hilt and positioning her arms to ensure her form was just right.
"This time," said Xander, "you can train right next to me as an equal, instead of swinging your sword alone from the depths of the fortress."
Corrin momentarily froze; her older brother's eyes were intense and fierce. After a moment, she finally chirped, "R-right!" But for some reason, the prospect made her feel nervous.
"En garde!"