(First, a hearty thank you to Spandex Justice for the wonderful comments. Your bribe is on its way)
Like many young men of my generation, Star Trek 2: The Wrath of Khan had a formative influence on me. Everything from the Kobayashi Maru to snarling "From hell's heart I stab at thee" to my mom for serving me decaf coffee...the character of Khan was, for many, the anti-Shatner: a man obsessed with a dead world, a dead wife...and the person who kept him from his destiny.
I'm not a Star Trek novel guy - ok, if it's at the library, and I like the cover, I'll check it out. So when I saw Volume One of The Eugenics Wars...well, out came the card. Friends, if you dig Trek, you have to check out Greg Cox's Khan Trilogy - Volumes One and Two of The Eugenics Wars, as well as To Reign In Hell, which takes place between the Trek episode "Space Seed" and ST:TWOK.
Now, I know what you're thinking - "Wait a minute, Gordon, I don't remember any genetically advanced supermen trying to take over in 1996? How can you do a war that never took place and make it realistic?" Well, in terms of the genetic advanced supermen taking over, I beg to differ - but Cox gives us the Eugenics War as a shadow war, playing out in secret amongst other tragedies of recent history. Mixing Trek trivia with the history of the past 30 years, Cox provides us a context for Khan's rise - it may be glorified fanwank in the eyes of some, but it's cleverly written glorified fanwank. Sure, there are some badly chosen tongue-in-cheek moments ("Welcome to Chrysalis Island" anyone?), but by the end, when Khan rockets off into the unknown, we know the future he will face....at least, part of it.
The crowning touch, however, is To Reign In Hell, which covers the "wilderness years" of Khan on Ceti Alpha V. It answers a lot of questions, but also shows us how Khan went from the relatively narcissistic leader to a man burning with obsession for Kirk. Yes, there is a framing sequence with Kirk, but that's the weakest part of the book. (And all three books are very easy, quick, and enjoyable reads). In short, this trilogy thoroughly explores Khan's character, and by the end, we know the outcome - but the journey there is what's most important.
Which is always been the heart of Trek, both TOS, TNG and DS9 - it was never about spaceships, or utopia, or even hope for the future. It was the constant reminder that, as we go beyond our limits, we learn more about ourselves, and that the greatest discoveries do not lie without, but within.