Would that be Mary Sue Piper ?
I keep hearing that, but Carey's Piper novels were actually more about doing the same sort of thing TNG's "Lower Decks" did -- showing
Star Trek from a fresh perspective, letting us see how our familiar heroes looked to the people who served under them. It was also a bit like the original, abortive idea for the animated series, focusing on younger counterparts to the established leads (Piper/Kirk, Sarda/Spock, Merete/McCoy, Scanner/Scotty). You could also make an analogy with the
Young Justice animated series, which is sort of a "Lower Decks" version of a Justice League series.
I guess you could say it's similar to the Mary Sue phenomenon in that there's an element of wish fulfillment in the first-person perspective -- "Imagine you were a crewperson serving under Kirk and got to learn from him and have adventures with him!" But strictly speaking, I think what makes a Mary Sue is that it's badly handled wish fulfillment that aggrandizes the author-surrogate character at the expense of the leads. Piper and her friends are several steps behind Kirk & co. throughout the books and are much more naive, needing to learn from the veterans. So I think it's ungenerous to apply the Mary Sue label.
I also remember a character named Mandala Flynn of Hunters Squadron (in the Vonda N. McIntyre adaptations ?) who I liked - does anyone know if she was seen again ?
Mandala Flynn was introduced in McIntyre's
The Entropy Effect, the first original Trek novel from Pocket books back in 1981. She was the
Enterprise security chief and Sulu's love interest. Hunter was the captain of the border patrol ship
Aerfen and a romantic interest for Kirk, as well as a captain Sulu admired. Flynn and Hunter were referenced but not seen in McIntyre's movie adaptations; I believe that one or both of them were serving aboard what was called a
Galaxy-class ship (not to be confused with the TNG version), designed for intergalactic travel.