Madame Fourchette is Grace Cahill and Beatrice Cahill's private tutor. Her first (and last) appearance is Vespers Rising, where she was scolding Grace, asking why she didn't complete her assignment, and why she couldn't be like her sister. Grace says that Beatrice is one of a kind. Madame Fourchette then says Beatrice completed her assignment, yet Grace hadn't written a single word. Grace refuses to do her assignment. Then Madame Fourchette gives Grace a punishment. Later, when Grace is halfway through,she deciphered part of the Morse code message.
Later, she is briefly mentioned when Grace recalls from Madame Fourchette's french lessons, that Ancienne Medina(AM) refers to Morroco's old casbah.