Warning: Takes liberties with Byakuya's background (meaning it may not necessarily follow canon), especially with Hisana. I've only read up until chapter 255 or so, so I'm unaware of revelations regarding Byakuya after that.
"This perfectly still spring day/Bathed in the soft light/From the spread-out sky;/Why do cherry blossoms /So restlessly scatter down?" - Ki no Tomonori
They are married with little ceremony. She has no family to speak of, and not one of his attends – they are driving a point, and he knows it. They think he will back down because of propriety, but he doesn't. He presses his lips together until they are stretched over his face like two flat blades, and he ignores the conspicuously empty garden all around them, and completes the rites. She smiles at him, shyly, from the collar of her kimono, while the official declares her as his wife. One of her hands slips out from her billowing sleeves, and gently touches his arm.
"Are you happy?"
He looks at her, as tenderly as he can. She stares back evenly, awaiting a response. Carefully, he lifts her hand, and puts his lips to her knuckles, hoping that it will suffice.
The Kuchiki are happy when they are allowed to be, and never anytime else.
When he thinks about it now, even if she's already lying next to him, he doesn't know how she could not have been frightened. He did not know how to explain to her that he was going to make her his bride – instead he had said something about matters to be settled and consequentially, you will be moved to the Soul Society, and she had been dragged from her home, politely but firmly. He justifies it by telling himself it was not actually a home, it was the slums, and he had paid her more visits than he could ever spare if he were already captain; besides, she would have gone, willfully, if he asked. Perhaps. Probably. Because they weren't strangers anymore, although they did not yet know each other too well.
The trouble was, he did not know how to court her. He did not ever think he would need to. In the Soul Society the first families could have their pick of anyone they wanted, if they were considered respectable enough. No one expected the Kuchiki bocchan to desire a commoner – and they used that word, desire, as if that was all it was. He still remembers how she had knelt in the sand with her head pressed to the floor, and how he had tipped her chin up slowly so that he could see her eyes. There was dust everywhere and the road stank of fish and ruined fruit, and there was blood drying on his blade, and she was shaking, but she was beautiful and fragile and she blushed as she whispered, "Thank you, my lord."
He feels battered and broken and he knows it isn't the training, and it isn't worth it to think about it so much (but he still does).
Spring is his favorite season to train in, although the most reliable texts dictate that one should have no preference. Perhaps it is because his own blade can identify with the wind, the dewy chill, the pink-frosted cherry trees that line the grounds of his home. The blossoms seem both petal and blade at once, and the difficulty of deciphering the two makes sparring a little more challenging – and a little more exciting, too, when he dares admit it. In the cool weather he can fight shadows for hours on end and not feel tired, the swiftly spiraling blossoms serving as very tricky targets. Some afternoons she sits under the trees to watch him, observing the way his sword bursts into a million beautiful, deadly shards, all dancing in the wind.
"I can hear her crying," Hisana whispers. "Every night." He can smell the pollution in her throat, the dusty streets of Rukongai still clinging onto the scent of her hands, even after she has washed them over and over. He wants to tell her to stop searching, to let his men do the work, anything to keep her from that violent place where the people will kill her if the atmosphere doesn't first. He knows she wont listen – she has become almost fanatical with her search, ignoring the pretty clothes he has had woven for her, preferring instead her old threadbare yukata and straw slippers, so that she'll blend in better.
She notices his silence. "I'm sorry, Byakuya-sama; I shouldn't be troubling you like this." She rolls on her side, turns her face away from him, sniffling into her pillow. She is so unhappy; should he offer to send even more men out to aid her search, or should he just patiently listen, is that the role he should play?
She never stops calling him 'Byakuya-sama,' and she can't seem to bear crying in front of him. Whenever her eyes tear up, she looks away, so that he feels like there are a million walls, rather than a few bare inches, between them.
He knows about the little sister she has abandoned. He knows she has never forgiven herself; he knows that the nameless child cannot be blamed. That still does not stop him from resenting her ghostly presence when Hisana develops a fever and begins to cough, so that he hears the wheezing in her chest well into the night. Besides, he tells himself, watching her shoulders shake as she belches into her cupped hands, for all we know, the girl might be dead already.
It is their fourth spring together when her health begins to fail at an alarming rate. She coughs up blood on the blankets and is unable to sleep; instead she trembles all through the night, sweating, eyes turned watery and red with pain. From evening until dawn he stays beside her, against the doctor's recommendation ("Because we can't risk you catching it, Kuchiki-sama,") but during the afternoons he sticks to the usual training. He ignores the lack of her presence under the cherry boughs, and attacks the falling petals until his arms are aching. He shouts the words that will turn sword into flower, and flower into death; shouts because he knows no one is listening, until his throat feels raw. The blossoms are stained crimson in his vision.
"Find her," the words squeeze out of her lips in agonized little moans, but she's working very hard to form them, and he's working very hard to understand. "Be for her the good sibling I failed at."
"Yes," he murmurs, and then he lifts her hand and touches it to his lips. It is thin as a twig in winter, and just as cold. "Yes, I will."
There are tears at the corner of her eyes, but for once she doesn't turn away. Maybe she has finally outgrown her shyness; more likely she just doesn't have the strength. "And when you find her, will you please protect her?"
"Yes, I will." He feels cold, colder than melted snow, cold as her fingers, even if it's spring.
"Thank you, Byakuya-sama." She smiles, and pulls her hand away from his mouth, resting two fingers on his jaw. Weakly. "I'm sorry I couldn't make you happy," the tears slide down her cheeks in two gentle waves, like a practiced dance, like the brush of clear ink on her canvas-white face. "I'm sorry if I caused you pain." He shakes his head, carefully so that her fingers don't slip from their place on his skin, but she doesn't seem to notice. "These past five years…." She gives a long sigh, a sigh like a book closing, and he feels so afraid – "…were the loveliest of my life. Thank you." She gives a shudder – he feels it in her touch, nearly ice against his chin, and then her hand falls.
Her lips are still moving, but he can't make out the words.
He doesn't know if she repeats I'm sorry, or if she says Goodbye. Or I love you.
That is his punishment, for not learning how to tell her properly; for never telling her just how much she gave him a reason for sunrise and sunset, a reason to look at flowers and see beauty rather than banality; a reason to break tradition.
She is no longer breathing.
Rukia dies for the second time tomorrow. He imagines her curled up as a baby, crying for a sister that will never return, no matter how many times the both of them have tried. He knows that ache, he knows that sorrow, he knows that spring is over and has been since the day Hisana died. It is his wife that waits in anxiety, in a prison, watching the moon with eyes that only see the inevitable: death. He does not know whether he wants to kill her or save her – her, his little sister, the ghost of his only love a breathing presence in this household, and he will never escape, how can he end this, does he have any choice?
"Help me," he tells the empty space beside him.
He imagines her crying and turning away, and there are no answers except for the whisper of flowers dying on the moonlit garden outside.
A/N: Thank you for reading, and I hope you enjoyed. :D Comments would be greatly appreciated, especially regarding Byakuya's character. I'm considering a sequel which deals with Byakuya's search for Rukia, so any concrit on his characterization would be awesome.