I don't like the approach you've taken, though I do like what you are trying to do. This is neat, and sparks my imagination, but it feels too confined to the dogma of the MBTI model you are forcing your creativity to confine itself to. I'm sure you have your convictions, and I'm sure they are shared by many, but that makes me feel unwelcome.
Nevertheless, I'm something of a gatecrasher when it comes to conceptual models, so I'm going to be arrogant here and force my own approach into this thread. I'm going to take a wildly different approach than you have, one that I think makes it more fun, by turning it into more of a fantasy-based role-playing game. Let's, instead of approaching it in a pre-defined dominant-auxiliary pairing, approach it one function at a time, adding on addition functions as we see fit to form a kind of elementary chemistry of personal questing, which is modular and open to radical thinking.
Let's begin with the quest itself. I'm partial to the "monomyth" as an excellent metaphor for this, unless anyone objects? I'll go ahead and use that.
Let us break the monomyth down into the four functions, and two attitudes - four base role-playing-game classes which will be the four heroic archetypes of our questing, with four very different kinds of quests, and two "alignments" which will not remain static, but rather, represent the two halves of the monomyth cycle that the hero must "claim" for himself - he must come to be the king of both his inner world, and the outer world. He will confront challenges of both types - introspective and external - at various steps along his journey, in no necessarily sequential ordering, just whatever fate has in store for him, as the chips fall where they may.
So, our four base function "classes" will be (because I am also partial to D&D) as follows:
Intuition: Mage
Sensation: Warrior
Thinking: Thief
Feeling: Priest
Now, let us assume that each of these base classes is essentially a pool of various talents and abilities, and just as in reality, nobody is totally useless when it comes to everything but their chosen specialty. Thus, while a Mage is foremost a wizard, that is not to say he cannot swing a sword. It just happens to be that he is quite untrained at it, not having time to devote to such a pursuit in favor of his magic, and so he will never quite compare to the ken of a warrior who is a master at arms and skilled in all manner of martial and exotic arms and armor.
So the thief, who is quite the scoundrel, lives and dies by his wits and does not put much stock into the kind of "faith" that is the daily bread of the Priest, and likewise, the Priest does not have a stomach for the kind of unscrupulous trickery of the thief, being a man of the cloth and a devout servant of some divine principle that gives him a sense of justice and good will towards others.
As the hero progresses in his base-class he finds a certain set of secondary skills to be of particular value to him, coming from one of the other base-classes, or he simply delves deeper into his primary set and finds the other half of his dominant function thus becoming closer to a more "pure" type. This secondary interest of his rounds out his primary skill set, and he works towards one of several "prestige classes" that represent the combination of two classes. However, because our model is open-ended, and (because I have strong convictions of this) in reality a mage can study martial skills and become a warrior-wizard if he wishes, there is no need to restrict the pairing of functions at all. I believe, in reality, while it can be said that Jung was correct when he predicted that "intuition pairs more easily with thinking or feeling, but not with sensation for the two are at cross-purposes" - I do not believe that in reality, humans are anything but
stubborn and will do whatever they damn well please. So while it may take
considerably more effort to pull it off I see no reason why, at least in theory, someone with a strong preference for intuition might not, as time progresses, learn to balance themselves out with some devotion to their inferior function of sensation. Perhaps this is a cruel road to take, perhaps the most difficult and downright
neurotic road in fact, but nevertheless, there is strength in overcoming adversity, and so, it is just another of many ways to success.
So the personal quest of the person depends on their approach to self-mastery, which invariably is bound up in their attempt to master the world as well. And with this more open-ended fantasy model, the options for self-expression allow for any possible combination of functions. I believe this is important because we want to cover
all possible bases just in case there is some weirdo out there who doesn't fit into the proscribed religious dogma of MBTI enthusiasts or even Jung himself.
However, I hadn't intended to give an account of
every single possible pairing in this one post - just the preliminary explanation of my own idea that was inspired by this thread. I might come back to this and lay out my predictions of the motivations for ever single pairing and prestige class, and maybe develop this idea of the fantasy monomyth model further, assuming of course that
@Old Intern doesn't decide to knock me down and shoo me off because I've gone and done whatever I fancied with her original idea instead of played along with her original intentions like a good little forumite ought to do.