You are the adopted child, of two famous hashira.

In your previous care, you had been abused. Like, to the point of attempted murder.

Giyuu being the sweetheart he is, decided to take you in. Sanemi being an absolute bastard (whom would do anything to see Giyuu happy), decided to keep you as well.

They both do certain behaviours, to make you feel safer. For instance, they never raise their voices. At you or each other.

Giyuu: “Damn it.”

Sanemi: “Hm?”