Let’s face it, the romantic scene between the Romulan Commander and Spock [in “The Enterprise Incident”] was totally out of context. Any Romulan worth her salt would have instantly suspected Spock because they are related races. That was wrong…my biggest objection is the scene between Spock and the woman, because I really did not believe it. And I did not believe that the Romulan did not suspect Spock of something underhanded. She does know enough about Vulcan and Vulcans to know that something’s afoot.D.C. Fontana on changes made to her script for “The Enterprise Incident”, quoted in Captains Logs by Edward Gross and Mark A. Altman, 1995.
I think “The Enterprise Incident” is one of my favourite TOS episodes, and the Romulan Commander was so much stronger and more interesting than most of the other women guest stars we got to see. But I was really interested to see that D.C. Fontana had envisioned her as even smarter and less susceptible to romantic emotions than she ended up being on screen.