See
A Four Stage Literary Progression.
An author of a popular fictional series presses buttons by referring to earlier episodes. Characters and readers reminisce. (Alan Moore did this big time in his "last Superman story." See Life And Art II.)
When, in A Knight Of Ghosts And Shadows, I, Dominic Flandry is reminded of:
"...Persis d'Io as she had been when she and Flandry said farewell on a planet now destroyed..." (p. 344)
- this refers to Ensign Flandry, the first Flandry novel.
When we are told that Persis had never recontacted Flandry, not even when he:
"...well-nigh singlehanded put down the barbarians of Scotha and was knighted for it..." (p. 346)
-this refers to "Tiger By The Tail," the first published Flandry episode.
Let me conclude this post with two similar examples from Ian Fleming, then a peculiar one.
"'Remember that Moonraker job I was on a few years back?'"
-Ian Fleming, Thunderball (London, 1961), 17, p. 141.
Bond remembers:
"...the great battle across the baize he had had with Le Chiffre so many years ago."
-Ian Fleming, On Her Majesty's Secret Service (London, 1965), 2, p. 21.
A few years, so many years - but we are not told how many. Fictional time can be more fluid than real time. We can check the precise year of publication for each volume. In Royale-les-Eaux, Bond also visits the grave of "Vesper Lynd. RIP." (ibid.) Le Chiffre and Vesper are, respectively, the villain and heroine of the first James Bond novel, Casino Royale.
I have referred
before to the haunting ending of
Alice In Wonderland which refers to this work itself as a tale of long ago.