Star Trek: Blackout
When a Federation world suffers a planet-wide blackout, it's the S.C.E. to the rescue. While Commander Gomez and her crack team of engineers work to help keep the planet from falling into chaos, the ship's linguist, Bart Faulwell, is given a special assignment: find the Asarion linguist named Jewlan -- who triggered the blackout with what appears to be a weapon in an archaeological dig.
The Asarion people have a unique biology that causes random shifts from male to female. Faulwell's friendship with Jewlan, and her crush on him, is a minor diversion, at first, especially given the struggles Faulwell is having with his own relationship. But when Jewlan becomes Jolen, Faulwell finds himself with more than one difficult decision -- especially when the power outage worsens and threatens to destroy not only Asario, but the da Vinci as well!