We are reconsidering the first five of the fifteen instalments in the Flandry period of Poul Anderson's Technic History and asking which persons or planets introduced in these instalments either reappear or are referenced later in the series. These five instalments are:
Ensign Flandry
A Circus Of Hells
The Rebel Worlds
"Outpost of Empire"
The Day Of Their Return
Ensign Flandry introduces:
Dominic Flandry, series character
Crown Prince Josip
Miriam Abrams, a child in a picture seen by her father but later Flandry's wife
Max Abrams, later remembered by his daughter
the land Starkadians, including Dragoika who reappears in "The Game of Empire"
John Ridenour who reappears in "Outpost of Empire"
Persis d'Io whose son by Flandry appears in A Knight Of Ghosts And Shadows -
- but does not introduce Merseia or the Merseians because:
Falkayn's team had been on Merseia in "Day of Burning";
Merseians had joined the Baburite Space Navy in Mirkheim;
the Merseian Roidhunate is a distant but growing threat in The People Of The Wind -
- or the Terran Empire which:
had been announced in "The Star Plunderer";
is expanding in "Sargasso of Lost Starships";
adjusts its frontier with the Domain of Ythri in The People Of The Wind.
A Circus Of Hells introduces:
the planet Talwin which is mentioned in The Day Of Their Return and reappears in A Knight Of Ghosts And Shadows;
Aycharaych of Chereion although only as mentioned by a Merseian;
D'jana whose psychic power will possibly influence Flandry in The Rebel Worlds and A Knight Of Ghosts And Shadows.
The Rebel Worlds introduces:
the planet Dido in the Virgilian System;
Josip now as Emperor although this time off-stage;
Vice Admiral Kheraskov, later mentioned in A Knight Of Ghosts And Shadows -
- but does not introduce:
The planet Aeneas which had been mentioned in "The Problem of Pain";
the planet Shalmu which had been mentioned in "Sargasso of Lost Starships";
the Ferrans, one of whom had appeared in Satan's World.
"Outpost of Empire" introduces:
the planet Freehold which is later referenced in "The Sharing of Flesh."
The Day Of Their Return, set on Aeneas, introduces:
Chunderban Desai who reappears in A Knight Of Ghosts And Shadows;
Aycharaych in person, destined to become Flandry's adversary in "Honorable Enemies," "Hunters of the Sky Cave" and A Knight Of Ghosts And Shadows and to be referenced again in The Game Of Empire;
the Aenean rebels some of whose descendants rejoin interstellar civilization in "Starfog."
That is one massive collection of connections and I have probably missed some.