Manse Everad And Wanda Tamberly

Poul Anderson's original Time Patrol tetralogy established a pattern. Each story featured the same viewpoint character, Manson Everard, each time accompanied by a different colleague: Whitcomb; Denison; Sandoval; van Sarawak. Three later stories featured different central characters, Nomura, Farness and Wanda Tamberly, but with Everard still present in a sort of elder statesman role. ("The Year Of The Ransom," which introduces Wanda, is more complicated but I am trying to summarize.)

When Anderson wrote the long Time Patrol novel, The Shield of Time:

Parts One, Three and Five introduced a new unifying character, Guion, in conversation with Everard, then Wanda, then Everard;
Part Two mainly featured  Everard;
Part Four focused on Wanda;
Part Six featured both and reintroduced Denison.

"Star Of The Sea" returned to the pattern of Everard accompanied by one newly introduced colleague. However, Everard retained his elder statesman status and, on this occasion, the new colleague was not another guy but Janne Floris with whom Everard begins and ends a relationship before meeting Wanda.

But this summary does no justice to the many other Time Patrol members from different eras who pass through the series, e.g.:

a veteran of the Martian war of 3890, teaching spaceflight at the Patrol Academy;

Epsilon Korten, born in twenty ninth century New Edom on Mars, scholar of Semitic texts and veteran of the Second Asteroid War, now director of Jerusalem base between the birth of David and the fall of Judah;

Kwei-fei Mendoza, a doctor on the Moon in 2319.

In The Shield Of Time, Wanda becomes the second main continuing character of the series. It may be worthwhile to reread her various dialogues with Everard.