Ciana was born in 2228, and while growing up discovered an interest in psychology. When she was old enough to enter Starfleet she signed aboard a starship as an assistant psychologist. However, she soon realized that there was not a promotion chain aboard a starship as a psychologist, and despite loving space duty, she applied for a transfer to command.
By 2269, Ciana had been promoted to Vice Admiral and was serving as an aide to Admiral Heihachiro Nogura. Due to her training in xenopsychology, Starfleet Command's relationships with non-Human species fell under her purview.
In the same year, Ciana first met Captain James T. Kirk while the USS Enterprise was docked at Starbase 25 for ten days of shore leave. Her primary assignment was to consult with the base's commanding officer, Commodore Cohen, on plans to begin Federation colonization efforts in the sector. However, she was also ordered by Admiral Nogura to visit Captain Kirk in order to assure him that, although the Enterprise was in the final year of its current five-year mission, no decisions about the future of his career had yet been made. It was during this meeting that Ciana admitted to Kirk that she had wanted to meet him for some time, and Kirk noted that Ciana appeared to flirt with him throughout their conversation. (TOS novel: Allegiance in Exile)
By 2270, Ciana was head of a special diplomatic division at Starfleet Headquarters, and was directly underneath Admiral Nogura in the chain of command. Despite having a choice assignment at Headquarters, Ciana wanted to advance her career further by being appointed as Starfleet's liaison to the Federation Council. Despite repeated requests to Admiral Nogura, Nogura thought that Ciana's directness did not lend to a successful career in diplomacy.
So in 2270, she successfully lobbied for Captain Kirk to join her department so that he could teach Ciana all of the diplomatic tricks and traits he perfected during the five years he commanded the Enterprise. While Kirk didn't want to be tied to the Admiralty, Ciana was able to persuade him by promising to do everything possible for Kirk to command the Enterprise again when the refit was completed. (TOS novel: The Lost Years)
Ciana died in 2273 in a transporter accident during the rush to make the refitted Enterprise operational in time to intercept V'Ger before it reached Earth. (TOS movie, novelization & comic adaptation: Star Trek: The Motion Picture)