Disclaimer: I claim little credit for this one-shot. The story of Bleach is by Kubo Tite and he claims it, not I (how I daydream it to be true though.).
Title: Hisana
Kuchiki Byakuya was a passionate man. He was a man who acted on his feelings alone. A shinigami, vice captain of Division 13, and a young master of the Kuchiki noble family.
Hisana was a woman without a surname. A plus spirit, living at the sidelines of Rukongai. She had abandoned her younger sister for her own survival. And for this, she always felt regretful of it. So she had not stopped looking for her. Her biggest wish is to find her and apologise.
By fate, they met. He was sent on a mission to capture an 'evil' hollow which catches plus spirits as his meals. She was caught by it. Her beauty captured his eyes, the silky look of her hair captivating him. She grabbed his attention. And he saved her. Injured by the hollow, Kuchiki Byakuya tended to Hisana. They fell in love.
And she became Kuchiki Hisana. Going against the wishes of his parents, he insisted on their marriage. Even as Hisana told him that he may have regretted to love and care for her, he did not give up. He did not feel any regret or blame on himself as his parents were angered to death too. He swore to protect Hisana, keep her alive till the day he dies.
Five years. Five years of marriage. Five years of living together. But they had not become one at all. Hisana rejected to be loved by Byakuya physically. She kept her distance from him. Because she thought that she did not deserve to be a mother. Not when she had abandoned her baby sister in the wilderness. She did not feel deserving to be a mother.
Yet Byakuya did not mind as much. He still cared for her. He even helped her to look for her sister, helping her in any way he could for her wish to come true. Even if it made him ignore some duties of his vice-captaincy.
Fortunately, Captain Ukitake of Division 13 did not mind too. He tried to understand Byakuya's feelings towards Hisana. He was moved by the vice captain's love towards his wife.
Then, disease struck. It was a disease struck deadly to the weak spirits of the soul society. And Hisana ignored Byakuya's warning not to go out to the streets alone to find her sister. She was struck by the disease then. She fell ill. And no doctor could save her. Just as no one could save the other spirits who also got the disease.
For the first time in his life, Kuchiki Byakuya cursed. If it were some things that he could have never done prior to his meeting with Hisana, it would be going against his parents' wishes or swearing or cursing on his lack of luck. It pained his heart.
He had sworn to protect Hisana, but failed. He wanted to live with her forever. But reality just seemed cruel even in this soul society world. She died. Kuchiki Hisana died in his hands. He could not save her. She could not find her sister.
But she gave him her wishes to find her sister and to get her to be his sister. For this, Byakuya felt a bit unhappy. Were her feelings for him always for him to help her succeed her wishes? Then he realised. He had forced her to marry him. Could he have expected her to love him when all she could ever give were her feelings of gratitude towards him?
It was then he realised a cold hard fact. Emotions do not matter much.
Owari
Author notes: Byakuya OOC here. But this is before the time we seen him in manga or anime. So he could have changed. Review and I'll respond back to you individually :P That'd be personal :D