This isn't the first time she's heard about it.
Even after allowing her adoption into the Kuchiki family, the head noblemen in charge of the clan never treated her as much more than a peasant. Once a rukongai brat, always a rukongai brat. They spoke in front of her almost like one would a servant – like she was just another piece of furniture, or a dumb animal. No, she had long known of her nii-sama's growing need for a wife.
She just hadn't expected to be so intimately involved with the problem.
"W-what? Nii-sama, I couldn't possibly-"
"I do not wish to pressure you into making a decision," he said in his accustomed manner – stoic, cold, distant. "I simply wished to inform you of my choice, and our family's expectations."
She knew that with the Winter War approaching, the nobles would expect her nii-sama to marry in order to produce an heir. After all, they couldn't possibly let their illustrious clan fall into history simply because young Byakuya didn't marry. He had had his fun, marrying that girl from the rukongai and then adopting her sister. Now was the time to take his duties in hand and settle the unfinished business that fell to him as the Kuchiki heir.
She realized that it also fell to her, being the adopted sister of her nii-sama. And after all, how could she refuse after their kindness?
"Of course, Nii-sama. But there is no need to wait." She swallows, earnest eyes meeting his. "I will marry you."
-X-
The wedding happens quickly.
The nobles, evidently always anticipating the event, had everything already prepared. Rukia's wedding kimono was quickly made – only the very best for the young Kuchiki bride – and the other details were readily taken care of. All of the Gotei Thirteen captains and vice-captains were invited, along with the other noble clans of the Soul Society. There was no time to tell her friends in Karakura Town.
The ceremony is beautiful but long. Rukia should have been concentrating on the words the officiator was speaking, but her mind wandered. She recalled the look on Renji's face when he saw her in her kimono, and she recalled how he turned away. It hurt. She wished she could make him understand. How she couldn't bear to refuse her nii-sama's wishes, not when he had been so kind to her. He saved her life and she would not return that kindness with anything less than her complete devotion.
"Bound forever, Byakuya and Rukia now embark together along life's journey. May their passage be filled with happiness, prosperity, and honor."
She turns to her former nii-sama, now husband, and they perform the san-san-kudo exchange of nuptial cups. They are married.
-X-
That first night is hard.
Rukia knows what is expected between those who are married, especially on their first night together. She knows what must occur between a man and woman to create a child. She most certainly knows what is expected of the new couple. What she doesn't know is that it isn't all about facts, and that feelings of one sort or another can help. Or harm.
She can only think about how she doesn't feel anything. Not physically – she could feel all the sensations, and they were pleasant enough. But emotionally, she is an empty cup, unprepared and lacking the right sort of love needed for this act. She doesn't know what's wrong. She loves Byakuya as her nii-sama, so what's so different about that love compared to this love? Or is it because she can't help but thinking about a certain brash, red-haired man? The one she's always been at least a little partial to, no matter their differences and arguments?
When it's done, Rukia clings to Byakuya. They sleep close to each other that night, though she is obviously holding on tighter, grasping for something she can't quite reach.
-X-
His words hurt her.
She knew he wouldn't quite comprehend her actions and motivations. He was never forced to understand the aristocracy like she was, and she knows he doesn't care to. After all, she grew up with him; survived with him. She should know what goes through Renji's head. What she doesn't expect is his harsh speech and his painful accusations. She certainly doesn't expect his admonition of love.
"Renji-"
"No, Rukia," he cuts her off, looking her in the eyes. "You married Byakuya. What more is there to say?"
And he leaves her there, standing under the cherry tree, fallen petals littering the ground around her feet.
-X-
The sacrifices are almost more than she can stand.
As a nobleman's wife, the Thirteen Court Guard Squads are out of her reach. She was honorably discharged from the thirteenth division to pursue her marital career. There would be no more missions, no more striving to make herself worthy of Kaien, no more rendezvous in the living world. Until he died, she would not see Ichigo again.
It wasn't proper for a Kuchiki woman of her standing.
She slowly learns about the world she's come into; the ordering of the household, tracking costs, and generally keeping herself busy. She finds herself with too much time on her hands, time her brain uses to think. She doesn't want to allow herself that luxury, and she immerses herself in her new role. While Byakuya is gone, she picks up new hobbies appropriate for a noblewoman. She discovers that there aren't many.
She tries her hand at painting and poetry, but hers is not an artistic temperament. She learns of the art of flower arrangement, and finds herself spending hours upon hours picking from the assortment of flowers the servants have clipped for her. She puts them in decorative vases, trying to find the right combination and composition. She finds one she likes but ends up throwing it away, only to start anew. The old one reminded her too much of someone, she told herself. This time would be different. But once she finishes the new one, she disposes of that one, too.
She doesn't get visitors. They're all too busy with their careers, just like the one she threw away. Slowly, she finds herself slowing down. The days drag on, and she increasingly finds herself spending them in ways she can't quite remember. Had she really spent all day staring into the courtyard?
Byakuya simply believes she's adjusting. A Kuchiki noble must act and behave in a certain way. Rukia is simply learning to take up her new role. He doesn't see that her new silence is more absentminded than conscious decision, that her eyes are more glazed than calculated distance. The servants don't dare to approach him with their concerns about the lady, and how she sometimes cries when she knows he is not around.
Rukia goes through the motions, but she has to force herself. Even rising from her futon in the morning is a struggle more difficult that fighting off a Menos. Her legs and arms are like rocks, and she wishes she could just stop trying. But she knows what is expected of her, and she keeps a soft smile on her face when Byakuya is around, and she performs her wifely duties with everything that is expected of her.
Every morning she sits in front of her mirror and tells herself she's happy, even though her heart is slowly turning to black.