I'll get back to my Borg Long Game soon but first I wanted to finish re-watching
Discovery Season 5. Then I'm finishing re-re-watching
Picard Season 3 (I got up to Episode 8), along with "Regeneration" from ENT, before continuing. Those are important parts of what this is all leading up to.
In the meantime, an oldie but a goodie: My updated head-canon for the TOS Film Era. As of 2024.
2270: The Five-Year Mission ends. Kirk is promoted to Admiral. Spock doesn't want to be Captain, resigns, and goes back to Vulcan. Starfleet does something that pisses off McCoy and he resigns, swearing he'll never return.
2270-2273: Kirk accepted the promotion out of ambition but now he finds he hates it. He was made Chief of Operations but his colleagues and superiors challenge him at every turn. Kirk thinking on his feet out there on his own doesn't translate well into coordinating the activities of a fleet. Kirk becomes a walking, talking example of the Peter Principle.
Kirk tries to reunite with Carol Marcus, this is how David is able to remember him before TWOK. David isn't told Kirk's his father. After it's clear things aren't going to work out with Carol, Kirk gets into a one-year marriage with Vice Admiral Lori Caini. They don't renew their vows. Kirk is lonely and hates his job. By 2272, he
really starts to want the Enterprise back and tries to figure out how to make it happen. When the V'Ger crisis gives him an opportunity in 2273, he jumps on it. To quote McCoy, "You rammed getting this command down Starfleet's throat! You used this emergency to get the Enterprise back!"
2270-2273: Spock has become too Human-like during his time on the Enterprise, especially under Kirk, and he immediately has a hard time being accepted on Vulcan. To solve this problem, he undergoes Kholinar to purge all remaining emotion.
2273: TMP happens.
2273-2278: Second Five-Year Mission.
2278-2281: Planet of the Titans happens. Kirk is missing for three years. Spock is promoted to Captain.
https://forgottentrek.com/phase-2/planet-of-the-titans-the-film-that-wasnt/
2281-2285: With Spock already Captain of the Enterprise, Starfleet Command assigns Kirk to become an instructor at Starfleet Academy. Kirk eventually pulls strings to get the Enterprise assigned to Starfleet Academy, and Spock goes along with it. He really doesn't want to be Captain, yet can't find a place on Vulcan, so being First Officer of the Enterprise is the only place he sees for himself.
One of the cadets who trains on the Enterprise is Saavik. Saavik knows Kirk and Spock for four years by the time of TWOK. So, basically, they've known her from freshman to senior. She's the equivalent of a grad student in TWOK, which is why she has the rank of Lieutenant and is training to be a Captain. She's essentially at the Command School level by TWOK. Spock is her mentor. Kirk is an enigma to her. "He's never what I expect, sir. He's so... Human."
Kirk meets Antonia in 2282. He
doesn't resign from Starfleet. Taking this idea from
@JonnyQuest037 . At least not in 2282. He
considers resigning in 2284 and wants to propose to Antonia, but ends up doing neither. This is something he wants to do over in
Generations.
2285-2286: TWOK, TSFS, and TVH. The Genesis Trilogy.
2286-2287: Enterprise-A shakedown period. The only reason Kirk even has this ship is for PR reasons after he and his crew saved Earth from the Whale Probe. That and Sarek probably pulled some strings.
2287-2292: Kirk's one and only Five-Year Mission with the Enterprise-A.
2292-2293: Running out the clock before the crew retires and the Enterprise-A is decommissioned. Reaching a dead end with Starfleet since he doesn't want to go any further, Spock explores idea of following in his father's footsteps, which will eventually lead him to become an Ambassador.
2293: TUC happens at the beginning of the year. GEN happens towards the end.