As I study the Enneagram, it seems that each Triad is made up of a "core type" (represented by 3-6-9) from which two more specific expressions of the fixation of the core type are developed - one a more inwardly-focused/internally-oriented expression of the core type fixation (5-4-1), one a more outwardly-focused/externally-oriented expression of the core type fixation (2-7-8).
Everyone seems to have the most difficulty typing people who are one of the core types, and perhaps the reason for this is that, since they have a more general focus/orientation (ie, don't represent an "extreme" of that type), they are harder to categorize.
(Maybe kinda like politics - everyone knows what a bleeding-heart liberal or a staunch conservative looks like and can totally predict their actions and reactions, but no one can quite figure out where the centrists and moderates are coming from or what they will do next, lol.)
Does anyone else see it this way?
And I will have a follow-up question if the math in this post seems to add up, lol! Thanks!