Two Kinds Of Fiction

(i) The author starts with a blank sheet of paper or computer screen and can create anything from nothing although, if he creates a series, then he should keep it consistent.

(ii) The author contributes to an already existing series and, again, should remain consistent with what has already been written in this case by others. An episode of a TV series is an obvious example.

Poul Anderson, of course, excelled at both kinds of fiction: many original series, e.g., the Technic History, and many contributions to other authors' series, e.g., an Anderson trilogy in the Man-Kzin Wars section of Larry Niven's Known Space future history.

This is another parallel with Neil Gaiman. Gaiman's The Sandman was set in the DC Universe. Thus, early issues took note of then recent changes to the Justice League. However, a fictional universe is a big place and later issues did not take any account of events elsewhere in the DCU. Similarly, Mike Grell's Green Arrow, featuring a non-super powered hero, simply did not refer to anyone with super powers. One reference to Superman might have been to a fictional character although we know that Superman is "real" in that universe. In The Sandman, a stage comedian refers to the Batman and we know that this joke is told in a universe where the Batman is real although in this case the Batman himself remains off-stage.

Similarly, the Technic History is a big place. A story could be set in the Chicago Integrate of van Rijn's period, in the Archopolis of Flandry's period or on one of the colonized planets without in any way impinging on the historical events of the History. This would be one way to add substance to that series. Millions of people live their lives against the backdrop of that history and we could read about some of those lives. A few stories already move in that direction but it could be developed a lot further.