If you've never watched The Venture Brothers and you plan on doing so (or you haven't caught up with the 4th season, there will be spoilers, so be forewarned).
When I used to watch the old episodes of The Venture Brothers, I sort of idolized Brock Samson because he was a superbadass on that show. Hypercompetent, prone to awesome feats of endurance, strength and let's face it violence, Brock Samson seems to represent a certain ideal. He's tough, a hit with the ladies and a pure killing machine when he is unleashed, and it is like he was born for the job of an OSI superagent, and is genetically that guy down to the very core.
But when I thought about it really, Brock Samson is sort of a dick when it comes down to it. When you see flashbacks of him in college, he was always sort of one. Yes, he is a good guy, but I think he is what you expect from that universe's man's man.
But Henchman 21 started off as the antithesis of that model. He was a wimpy, cowardly geeky guy who just had an incredible run of luck and enough genre savvy to know how to survive his various errands for the Monarch. And he is really a geek. Like super geeky, and especially with Henchman 24.
And then Henchman 24 was killed and 21 vowed to change and become someone capable on the battlefield so no one close to him would ever die again under his watch. He turned himself from a flabby geeky nobody into a superbadass. He went from being one of many henchmen to becoming The Henchman, and even though he still works for a villain, he has become heroic and epic and perhaps more powerful than the lord he serves.
As a geek, he is sort of aspirational. He doesn't have the gifts that Brock Samson has, but he doesn't care... he devoted his energy to becoming a badass on his own terms and there is something noble in that, even if part of the reason he did so was to exact revenge on the people he felt were responsible for the death of his friend.
But if that formerly flabby tub of cowardice could turn himself into a superman who can kill his peers as needed, fight monstrous supervillains and make out with his his boss's hot wife in a short period of time, all while maintaining his essential geekiness. In that regard, he is still the same guy that hung around with Henchman 24 dissecting pop culture and arguing about how Smurfs propagate their species.
In the end, Henchman 21 represents a particular ideal. He went far beyond his formerly meager personal resources and became the embodiment of geekish success, and if he can do it, then any geek can. Huzzah!