Unohana Retsu knew when she went in to this battle that she wouldn't come out alive.
She knew that this would be her last fight, her last chance to feel that thrill, that incredible rush of adrenaline as her sword danced and twirled in flashes of red.
Red.
Red had always been her favorite color. Red like blood. Until Red had become boring. Bloodshed no longer excited her, the color was annoying: visible evidence of just how strong she was and just how weak everyone else was.
Red lacked challenge.
She had few regrets in her considerable lifespan. Her eyes met Zaraki's and she thought back to when they first met; to the hollow emptiness she had been feeling at being the most powerful of everyone she had ever crossed blades with until a boy, not even a young man, attacked her. The rush, the thrill of fighting a powerful opponent caused her blood to sing and she found herself enjoying the fight once again.
She found herself drawn once again to the color Red.
When he scarred her chest, she stared at the bright Red of her blood and remembered for once wondering if he was more powerful than she, if she had finally, finally met someone who could challenge her, beat her.
She may have fallen in love with the Red.
She found it strangely fitting, as she closed her eyes to the bright Red splashes of blood - her blood - on his face, that he was her beginning and also her end.