Meanwhile

A fictional realm gains depth and solidity when its readers learn what is happening in different places at the same time:

in Robert Heinlein's Future History Vol II, an accident occurring in one story is mentioned in another;

in Poul Anderson's Technic History, John Ridenour, who had been on Starkad with Dominic Flandry, visits Freehold while Chunderban Desai, working on Aeneas, reads an intelligence report written by Dominic Flandry;

in SM Stirling's Emberverse series, one volume describes a "Quest" whereas the following volume tells us what had been happening back home meanwhile.

The central character of some installments can be mentioned tangentially in others:

Heinlein's astrogators refer to old man Harriman;

in the Technic History, one character has seen Nicholas van Rijn on their equivalent of television;

in a later period, another character has heard of the exploits of Admiral Flandry.

These observations are inspired by a tantalizing passage in Ian Fleming's The Spy Who Loved Me. Uniquely in this novel by Fleming, the heroine narrates for nine chapters before she even meets James Bond. However, she does tell us this:

"I was still living with Susan. She had got a job with the Foreign Office in something called 'Communications', about which she was very secretive, and she had a boy-friend from the same department..."
-Ian Fleming, The Spy Who Loved Me (London, 1980), Chapter Four, p. 50.

As the Japanese say, just so.