Naamah-darling posits the beginnings of bean nighe folklore
I wind up elbows-deep in the sink washing my underwear out in cold water, feeling very much like one of those creepy Irish ghosts that washes bloody clothes in the river, supposedly presaging the observer's death by violence. Now I will always imagine that the legend of the bean nighe was inspired by some poor woman just trying to dealing with her fucking period laundry. Some guy walking past saw her at it one day and said something smart-mouthed, and the woman said something snarky and Celtic, like "May all the blood that has ever come out of my vagina soak your clothes in the coming battle because someone stabbed you in the face." And he died in the battle, and his friends remembered what she said, and it entered folklore as A Thing. Moral: if a chick is washing blood out of clothes, leave her alone. There is probably no reason for her doing so that does not involve her having a bad day, and you possibly having a worse one.
context is washing blood out of her clothes and sh*t off of her cat...