Now who's the Animal?

In the many years Unohana has been the captain of division four, she has seen some very odd hollow-related injuries. All sorts of poisons, venoms, and acids with a wide variety of symptoms. Each time she is faced with a new challenge, and each time she's conquered it without fail.
Until now.
Now Byakuya Kuchiki, captain of the sixth division himself has been infected, and his lieutenant pays the price. Nothing either of them do will remove the guilt. Because of one little mistake and a few moments of pleasure, their relationship will never be the same.
But perhaps it's for the best...?

Or, for those out there like me who prefer their descriptions much more simple....
Byakuya turns into a sex zombie and accidentally fucks his lieutenant. Hard.
Oops.