In the island
Due to the ingestion of Medusoid Mycelium (possibly)
- "All I want is the simple life my mother and father had together, without arguing or keeping secrets."
- —Friday in The End
Friday is a girl, estimated to be six or seven years old, and is the only child on the island with the ability to write. She wears a white seashell around her neck in which she keeps her coconut cordial. She may have more of a free spirit than the other islanders, as shown when she walks into the camp wearing sunglasses (which are outside the strict dress code because Ishmael believes they can be used as a weapon).
At the end of the book, she rides off in a boat with her fellow islanders and it is implied that she met her fate by being poisoned by the Medusoid Mycelium.
- Like her father, she is named after a day of the week (notably the one after her father's name).
- Friday's only appearance in the series is the thirteenth book; or The End, a reference to the unlucky date of Friday the thirteenth.
- There is a theory that Mrs. Widdershins and Miranda Caliban are the same, meaning Fiona and Fernald are Friday's siblings or half-siblings (depending if Thursday is Captain Widdershins or someone else.)
- She is right-handed as an illustration of her right hand is shown drawing in the European version of The End.