Between blotch and blok

I've been told that my mother's cat tried to throw my father out of the bed when he first moved in. (She (Cinders) was an ex-experimental animal from the vet school, where my mother worked at the time. She was a control animal whose job was to live in a cage and have blood samples taken daily, and my mother's boss warned that she was unlikely to make a good family pet - but she did.)