When it comes to Star Trek pairings, the most appreciated in fandom is between James T. Kirk and Spock, even though, as far I'm aware, there's no official material about it, just them being so close that it seems absurd for them to be anything but, plus the whole mess of how Spock's engagement ended (and T'pring proved once and for all that Romulan deviousness is a legacy of Vulcan culture) and Kirk having no clear stable relationship in either the show or the Beta canon... Except for one, with Ael i-Mhiessan t'Rllaillieu, a Romulan khre'riov (commander-general. Closest equivalent rank in Starfleet would be a commodore), first his greatest enemy (this enmity ended well before Khan came back) and later his ally due the dishonorable actions of the Romulan government, with an awful lot of people, both in Starfleet and among the Romulans, assuming they were an item long before they actually hooked up - after the Romulan Free Movement surprise elected her to the position of Empress of the Romulan Star Empire rather than allowing her to retire (it's the Romulans, they do that). And the best part? Well, Ael would provide a way for them to be married.
After all, according to the writers of STP, Romulan marriages are always threesomes, in any configuration of gender... And considering Ael is a widow and has no living children (her husband died in a "misunderstanding" with the Klingon, status of the other spouse is unknown, and her only son Tafv committed an action that required her to kill him for honor, rather than let him die of the mortal wounds he suffered in the process or allow anyone to give him a mercy kill), Kirk is ALSO a widower and divorced (long stories, one involving an amnesia) and was estranged from his son, and Spock's engagement had crashed and burned, they could have easily gone for it. Because, after all, a monarch should be married, and who else could be worthy of the Empress of the Romulan Star Empire than the one man that could match her wits and his spouse in everything but name?
And as I typed the above, I realized that Carol Marcus must have had quite the headaches after that. After all, Jim respected her wish for him to stay away from their son, Spock would follow his lead, but the EMPRESS OF THE ROMULAN STAR EMPIRE? Nah, one of David's birthdays Carol and David Marcus would have seen a warbird decloaking right next to wherever they were because Empress Ael wanted to meet her husband's son at least once and that was the best possible day (both because it was the most joyous, and as a power move), and THAT was how David found out who his father was.
And as I typed the above, I ALSO realized that there were CONSEQUENCES for the Klingon Empire for the Genesis Incident. After all, after the Romulan Civil War Romulan-Federation relations were at their historical best, and then a Klingon commander KILLED THE EMPRESS' STEPSON before being killed by one of her husbands (and the stepson's father). Heads must have rolled to prevent the Romulans from attacking and bringing the Federation along...
