And D.C. Fontana wanted it to parallel it even closer.
Fascinating! The episode (IMHO) is wonderful as it is but for whatever reason(s), I'm glad it was kept at the level it was. I'll post a link below, which appears to cover some of her original draft - which definitely parallels the issue a lot more, if the teaser is hinting at the Enterprise just going for an observation mission to see if the Klingons are giving their ship technology to the Romulans (giving the Romulans an edge against the Federation), instead of Kirk acting wack and going headstrong into Romulan territory about a cloaking device. The espionage and Captain Wack aspects still felt more firsthand exciting, showed another aspect of Kirk being mindful of his crew.
The finished episode shows a lot more than just seeing if Klingons are working with Romulans, it's clear (hinted at in the 4/19/68 draft) that they were but felt that was secondary to the new cloaking device. It's a shame season 3 didn't build on all this, unless that was Fontana's goal - to do this in steps (show alliance forming, later culminating in a new cloaking device on top of all that. Either way, both editions intrigue but the finished edition with the added dimension for Kirk, the new cloak, and the Romulan Commander trying to get Spock to defect - if he or Sarek was going to be the one tempted to cross over?)
What that site reveals clearly shows how much Fontana loved the show and her characters and depth into exploring Vulcan lore. Even the TAS episode where she fleshes out ideas mentioned briefly in "Journey to Babel" regarding Spock as a child... and having seen all of TAS a year or two ago and in awe over the quality of the stories (and only just found out now she was the story editor!!)... Fontana, was so much an asset to this franchise, even for scripts where she withdrew her name and had a pseudonym put in - the base ideas were still hers until a certain point.
Never knew it was Freiberger's idea to have Romulans using Klingon design (thus hinting at a new alliance, which could have expanded storylines as well... that and it made TOS-R look even more stunning as we saw both types of ships surrounding the Enterprise. I wonder what happened to the Romulan ship from season 1 and why it never made a return...)
https://startrekfactcheck.blogspot.com/2016/05/dc-fontanas-story-outlines-for.html
And on Memory Alpha, I had no idea it was originally to be Kirk and McCoy doing the stealing of the cloak, and their outline of the story suggests Kirk's sanity may have been tested in a way other than feigning insanity to get the crew off the hook. Now that would have been way-cool.
And she wrote in a novel how Spock can go get jiggy (the 7 year cycle is of
fertility, they can technically "get busy" any time.) This also lets Spock off the hook for "The Cloud Minders" as he's seen to be cajoling to Droxine and by then I doubt NBC got tons of fan protest letters the way they had regarding Spock and the Romulan Commander (or by fans bringing up "Amok Time" even though with Spock having opened up to Kirk, he may have had an epiphany and not being so high strung on discussing his species' pre-bedtime habits (or "snu-snu before snooze-snooze", Zapp Brannigan knows all about that!
)) Spock not being 100% Vulcan would also allow the inference involving his human side being a factor as well, something TOS might have benefited from but worked out okay regardless.
https://memory-alpha.fandom.com/wiki/The_Enterprise_Incident_(episode)
