Actually, the only functions that should be seriously considered are the Ego functions. Because every other function are mainly just consequences of the strength of those two.
And something i want to address, You should consider the whole type, and not just the subtype. A 4 is a 4 whether it's 4w5 or 4w3. An 8 is an 8 whether it's a 8w7 or an 8w9, same core motivations.
And well yeah, A types behavior comes from it's motivations...That's so obvious, it's best to be left unsaid. That's what the enneagram is for. But you can't say a 5 will go into a room and instantly withdraw.
Anyway from Personality Types:
" Basically, Eights are driven by the fear of being dominated, harmed, or controlled by others."
That can be translated as Hidden Agenda
or Leading
. Tell me how it can't...