"I am sick to death of the matter and the notion of any quarrel has made me feel quite ill. It is of course very unfortunate that my story was written first and read by people and if they express their astonishment it is a natural consequence and no fault of mine or any one else. I assume that you know me sufficiently to be sure that I have never alluded to the matter even to friends who have spoken of 'The Nixie'. I trust this matter is not making you feel as ill as all of us. Yours affectionately,
Katherine De Mattos"

Katharine Elizabeth Alan Stevenson de Mattos (1851-1939) was RLS’s cousin and Bob Stevenson’s sister. She was born to Alan Stevenson and Margaret Scott Jones. She married William Sydney de Mattos (b. 1851) and the couple had two surviving children. Katharine became an author, writing under the pseudonym of Theodor Hertz-Garten.

RLS and Katharine played together when they were children, and she visited the Stevensons’ home in Bournemouth.

Katharine had a good relationship with RLS until March 1888 when they quarreled over a story she had written. The quarrel came about when Fanny Stevenson published the short story “The Nixie”. W.E. Henley accused Fanny of plagiarizing the story from Katharine’s own. RLS took his wife’s side, hurting Katharine’s feelings and alienating himself from Henley.