the seven disintegrates to one and integrates to five. fives go to seven, if disintegrated. the "introverted seven" might be an introverted five. or it might be a seven, who is technically extroverted, but has grown a habit of retreating into rather introverted behavior for one-ish reasons.
that's just the theory, not my opinion about reality.
i have heard a rumor about "estp who are like intj", so i have looked out for such a pattern and found a few individuals who match that "description". they would live in their heads and be concerned with theories like stereotypical INTj, they would also bee interested in bodybuilding but without visible halla type of fun and with a more rigid technical approach to nutrition and stuff...
personally i can very much relate to the motive of the seven, but i just don't have to connect this issue of mine with typology. there is a live outside of type.
if theory would not insist, that sevens are extroverted, i would say, this issue of avoiding the pain of being locked into something, is more obvious or "bigger" in my live, than all the other issues of myself (which are topics of 6,5,4,9,1).
however my escape strategy is different from that of the seven, it has to be, because i don't have the skills of extroversion, which are the skills of this strategy.
i don't understand completely, why enneagram theory would insist to define the seven based on his escape strategy instead of basing the definition on the object of the fear, or even the cause of the fear.
the thing you escape from seems to be more significant to me, than the escape strategy...
but of course the strategy must be uncovered too, if the enneagram is supposed to deliver practical advice on how to overcome the fixation of the type.