Hmmm? Not sure I agree with your logic here. She is a high ranking Commander with the power to get Spock his own command. She willingly throws herself into the lion's den by jumping onto Spock when she hears the transporter beam activated during Spock's confession (ensuring that she will be unarmed and unassisted when she materializes with Spock on board Enterprise). She orders Tal to destroy Enterprise while she is on board her. She strikes me as pretty old-school when it comes to the whole "death before dishonor" philosophy.
I don't see that. Jumping into the transporter beam was an impulsive move that's hard to characterize a clear motive for, but I don't see how you can get "suicidal" from it. If anything, I think the writers' intent was more that she was a lovesick female who wasn't thinking clearly because she was gaga over Spock, and thereby let herself be not only duped but taken prisoner as well.
The order to destroy the ship was a tactical move mandated by military necessity; Kirk has given similar orders in similar situations, treating himself as expendable for the safety of the ship or the Federation, but that doesn't mean Kirk is culturally predisposed to suicide.
That sounds like it would be a pretty empty and un-luxurious room, Kirk might as well have sent her to the brig!
Appearances matter. A prisoner of war wouldn't expect luxury or comfort, but confining her to quarters would let her retain some semblance of dignity and privacy that confinement to the brig would not.
How do we know she didn't? The episode ended only a couple of minutes after the last time we saw her, and the character never appeared again in any canonical installment (although numerous tie-in books and comics have established her as either still alive in later years or executed in disgrace by her government).
I have never read these novels, but would like to. Can you give me the titles of them?
Ohh, there are a ton of them. In the early years of Trek Lit, the Female Romulan Commander was pretty much the most popular guest character to bring back, or at least to be alluded to in other Romulan-themed novels. Let's see, here's a probably incomplete list:
The Price of the Phoenix and
The Fate of the Phoenix by Sondra Marshak & Myrna Culbreath (from Bantam) show the Commander as still having her rank and position and becoming a tenuous ally of Kirk and Spock in dealing with the villain Omne. In the second book, she's named Di'on Charvon. (These books are widely reviled, though, for their fannish excess, corny romance-novelish writing, and slashy subtext. Read at your own risk.)
Black Fire by Sonni Cooper has a brief cameo by the Commander during a portion of the novel wherein Spock has apparently defected from Starfleet to become a Romulan officer, following his stint as a space pirate. (Seriously. It's one bizarre book.) Basically she just comes up to Spock at a party and tells him she was stripped of her command because of him.
Yesterday's Son by A. C. Crispin features Subcommander Tal, who seeks revenge on Spock for his Commander's disgrace and execution.
The Rihannsu novels by Diane Duane (
My Enemy, My Ally, The Romulan Way, Swordhunt/Honor Blade, and
The Empty Chair) feature a different Romulan commander named Ael who is the Commander's cousin; in these books the Commander is established to have been disgraced and exiled.
Dwellers in the Crucible by Margaret Wander Bonanno leaves her nameless, but establishes that she was disgraced after the cloaking-device incident and needed many years to fight her way back to starship command (the novel is set a few years before TWOK). It's more or less in continuity with the Diane Duane books, although only the first Rihannsu book had been written yet when it came out.
Killing Time by Della Van Hise names her Thea and makes her Praetor of the Romulan Empire (a
secret Praetor, no less, since in this book alone, the Romulans are suddenly sexist and wouldn't tolerate a female head of state).
In a more recent series of novels by Josepha Sherman & Susan Shwartz (
Vulcan's Heart and the
Vulcan's Soul trilogy), the Commander is named Liviana Charvanek and is shown to be still a starship commander in the early 24th century, eventually rising to the head of Romulan Security by the post-Dominion War era.
The TOS novel
Section 31: Cloak is set a few months after "The Enterprise Incident" and shows her still in Starfleet custody.
The IDW Comics miniseries
Star Trek Year Four: The Enterprise Experiment by D. C. Fontana features the Commander, showing her being released in a prisoner exchange and then getting her command back.
However, if she is later executed by the Romulans doesn't this suggest that she was expected to do the "honorable thing" and kill herself?
Well, as the list shows, there's pretty much only the one novel that asserts she was executed. The majority show that she was punished and demoted/disgraced but still alive and able to win back her status and then some, while a few (the
Phoenix novels,
The Enterprise Experiment, and especially
Killing Time) show her suffering no significant setbacks at all.