This is the episode that established Khan Noonien Singh as a total pimp and Leonard McCoy as possibly the bravest man on the crew of the Enterprise. James T. Kirk comes up a little short when compared to these two but you can't win them all. How can you compete with a superman, a product of selective breeding, who can charm a Starfleet officer into betraying her shipmates, and a man who calmly tells this superman, who has one hand gripped around his throat and another hand holding a knife to his jugular, to either choke him or cut his throat and then proceeds to give him detailed instructions on the most efficient means of doing the latter?!?!
Who is Khan? He and his followers are all genetically engineered supermen who attempted to take over the world and, having failed in this attempt, apparently fled Earth in the late 90's during the Eugenics Wars. Strangely enough, I have no recollection of there ever having been what Spock referred to as “your last so-called World War” in the 90's but I was in graduate school back then and might have been a bit too preoccupied to notice the rise and fall of a Sikh dictator named Khan.
There's a lesson in there somewhere. As a wise man once said, “Life moves pretty fast. If you don't stop and look around once in a while, you could miss it.”
Going back to Space Seed, Khan and his followers are found by the crew of the Enterprise aboard the SS Botany Bay. The Botany Bay is a sleeper ship, in case you're wondering how these fugitives from the 90's managed to survive into the 23rd century. To make a long story short, Khan is revived but no one knows who he is, at least not right away, which gives him the chance to read all the Enteprise's engineering manuals and seduce the Enterprise's historian, Marla McGivers, who is intrigued enough by this manly man from the 90's to help him revive his followers and take over the Enterprise.
Khan might have succeeded in his plan to use the Enterprise as a tool for world, or rather, galactic, domination except for some reason, he needed the aid of the Enterprise's crew to keep ol' NCC-1701 running. This makes absolutely no sense at all since he supposedly learned the workings of the ship by speed-reading its manuals, something which his followers could presumably do as well, so what need would he have for the cooperation of the crew? He would have been better served air-locking them except for the fact that Space Seed's narrative established him as being a benevolent dictator when he was in power.
Despite being a “nice” dictator, Khan decides to coerce the crew of the Enterprise into cooperating with him by torturing Kirk to death in the ship's decompression chamber. This serves to throw a much-needed glass of cold water in McGivers's face (metaphorically speaking, of course) and she rescues her Captain, allowing him to retake the ship and beat the crap out of Khan with the 23rd century equivalent of a lead pipe.
What can I say about this episode? Its only flaw as I see it is Khan deciding to torture Kirk. Not only is it supposedly out of character for Khan but it was unnecessary given what we know about him and his followers. Having Kirk thrown into the decompression chamber was basically a convenient excuse for McGivers to have second thoughts about helping Khan. Strangely enough, Khan seemed to be blindsided by McGivers turning on him, which shouldn't really have been all that surprising given that she had already betrayed her shipmates in helping him take over the Enterprise. Even stranger still, he decides to take her with him into exile after he and his followers are marooned by Kirk on Alpha Ceti V and, eventually, as we're told in The Wrath of Khan, even takes her as his wife.
Speaking of The Wrath of Khan, Khan looks strangely pale fifteen years down the road, given that in Space Seed it looks like Ricardo Montalban took a dip in a tub of walnut stain for the role. I guess fifteen years spent wrapped up in robes and living a troglodytic existence (you'll know what I'm talking about if you've seen the movie) will do that to you. And The Wrath of Khan is all one really needs to say when summing up Space Seed. Despite some inconsistencies in Khan's characterization, the fact that Space Seed made The Wrath of Khan possible makes it impossible for me not to forgive this little fault.