Finally watched Khan's ep from TOS.
I gotta say, why was he brought up as "Kirk's rival" in WoK? It feels more like he's the "adversary of the week" than an actual rival. Most of his great accomplishments are in WoK than in the episode he was from.
Khan was never Kirk's rival. He really was just "adversary of the week" until Harve Bennett thought he had potential to become something more.
Khan was a former King and an alpha male. He had a run in with Kirk and tried to be more alpha than Kirk, but he lost (all he won was one of Kirk's women, and she wasn't even Kirk's type). And then Kirk spared his life, and pondered the consequences of letting someone like Khan live.
20 years later, and Kirk has never given Khan a second thought. Starfleet has never given Khan a second thought.
A planet blew up, and Starfleet never cared. "Which planet blew up? Was it the one with the dangerous criminals living on it?" "Who cares, just list one of them as destroyed and move on."
Khan meets Chekov and he's mad that
"Admiral" Kirk has forgotten him and moved on with his life. He's even mad that
Chekov didn't remember him enough to tell tales of Khan's epic battles to his new Captain. Khan has been living with dreams of vengeance, but his "rivalry" with Kirk is entirely one-sided. Khan is Captain Ahab, driven by defeat to chase Kirk, the White Whale, a foe who's out of Khan's league and who isn't really even attacking. It's all in Khan's head.
Even Kirk's famous/infamous "KHAN!!!" scream was a lie. Khan wanted Kirk to suffer, and tried to leave him buried alive. Kirk knew he wasn't beaten, and there was no real rage (or whatever mix of emotions) in that scream, he just knew that Khan was desperate to hear Kirk cry out, and this would let Khan think he won, and make him drop his guard, while Kirk calmly plotted Khan's defeat. So Kirk said (yelled) what Khan wanted to hear.
Khan was never an equal, he was always Kirk's bitch. Khan thought he could kill Kirk if he paid with his own life, but all he succeeded in doing was killing Spock (who willingly sacrificed himself to save the crew). And left Kirk pondering his own arrogance.
Space Seed doesn't hold up as "the prequel to Wrath of Khan", it's just that when WoK came out, some people could point to it and say "Hey neat, continuity."