Since it’s Trek Week over on io9 I figured I would revisit The Animated Series (currently streaming on Netflix). The second episode “Yesteryear” is one of the best of the series and even was number 30 on the io9 list of top 100 Trek episodes.
The episode starts with a callback to “City on the Edge of Forever” as the Enterprise is assisting some historical research using the Guardian. When Kirk, Spock and a random redshirt return through the portal, they are surprised when no one recognizes Spock.
A little research shows that in this timeline Spock died as a seven year old child. It turns out the researchers happened to be looking at recent Vulcan history while Spock was away. Seven year old Spock was supposed to be saved from death by a visiting cousin who happened to look a lot like the adult Spock. But adult Spock was in the more distant past at the time the historians were looking so he didn’t save the young Spock and the timeline changed. (This is why your parents tell you not to mess around with time travel, kids.) To fix things Spock uses the Guardian to travel back and save his younger self.
There’s a lot more going in the episode besides that plot. Adult Spock gives some advice to his younger self about life as a half human. And a callback is made to another TOS episode, “Journey to Babel,” with the young Spock’s pet sehlat, I-Chaya. The pet was gravely wounded during the beast attack that adult Spock saves young Spock from. This didn’t happen in the original timeline that adult Spock remembers. Young Spock is given a choice - I-Chaya can live but will be in great pain or the sehlat’s life can be ended quickly and peacefully. Young Spock makes the logical choice, the Vulcan choice, of letting the pet die. Not something you saw a lot on Saturday morning cartoons but an important step for someone who would later not hesitate to put the needs of the many ahead of the needs of the few (or the one) even at the cost of his own life.
I watched TAS when it aired back in the early ‘70s (while watching reruns of TOS on weekday afternoons). Many episodes are forgettable (though it was where I learned what Kirk’s middle name was) but there are a few standouts like “Yesteryear,” the only TAS episode written by Trek veteran D.C. Fontana.