Greffier
Reading the plot summary, one could think that the cat was named "Greffier".
In fact "greffier" is a colloquial (slang ?) term meaning "cat".
"Le greffier" is the secretary of a judge having authority to sign legal papers.
This signature is called "griffe" (scratch) and as cats have a tendancy to scratch anything, including expensive pieces of furniture, they are nick-named "greffier".