A Brief History of Unohana Retsu . . .
Retsu had endured wars before, of course, but this was the first one that had ended in defeat - and the first in some time that had affected her so personally. She had escaped from Hueco Mundo and hurried to the King's Realm as quickly as she could manage. In the end, the fighting was all but over by the time that she got there and all she could do was tend to the wounds of those that still lived. Which did not, sadly, include Yamamoto-sensei; he had already passed into death before she arrived.
Life returned to something resembling normal in the following weeks. After all, her division dealt with the mending of broken bodies on a daily basis; not much had changed there. But the atmosphere was different, ranging from wariness to outright hopelessness in all of those around her. Much of Retsu's time was spent trying to bring comfort to Isane, who had lost her younger sister in the war. And during all of this, she spent little time concerned over her own well being. She'd thrown herself even deeper into her duties than usual, working herself down to exhaustion before she slept. That way, she could avoid the darker thoughts that threatened to take her otherwise.
It wasn't healthy, and she knew it. But it took the worried stares and hushed whispers of many of her officers before Retsu acknowledged that she needed to pull herself together. Before, on those rare occasions that she had felt adrift, she had been able to confide in Yamamoto-sensei, and he would find a way to allay her fears. Now, she had no such father figure to turn to; it was time for her to finally grow up.
She forced herself back into a healthier routine, spent time with old friends when she could. These tasks were difficult at first, but she maintained her course, not only for her own sake, but for that of her division. And she noticed, as she slowly returned to her old ways, that morale within the division improved along with her. Perhaps many of their negative emotions had been magnified by her own sorry state. If she broke, then who was to say that those under her command might not? She would not have something so disastrous on her conscience.
But there is one aspect of her folly that she has kept - an even keener eye for detail. While things are peaceful at the moment, Retsu harbours no illusions about Aizen's new position of power; he surely has something else planned. She had noticed warning signs too late in the past, and she simply will not do that again. This time, she will see things in advance. And every now and then, she unconsciously fingers Minazuki's hilt, wondering if there might soon be a moment where she will be forced to step off the back lines and enter combat for the first time in many centuries.
She still isn't sure whether the thought bothers her or not.