What you describe seems very core ISFj and not a subclass. All ISFjs usually have autonomy as a prime directive, and this manifests itself in diverse ways; they will conduct themselves to achieve whatever form of independence is important to them. They certainly don't look for solitude but may end up isolated because of circumstance or specific decisions. They will try to change things when their expectations are not being met - first by indirect means but this can easily escalate. I don't see them deliberately creating circles but they can easily fall into one, provided their independence can be maintained; and, they will normally use whatever power they have to defend their values or those close. They can become very aggressive when normal tactics aren't working - some can be violent but this has more to do with how they've been raised.
a.k.a. I/O