I don't think you're talking about therapists intentionally triggering fear here, are you? Although that probably could happen, too. But when the (unconscious transference-countertransference) dynamic going on in the therapy interaction triggers fear in the client, thus activating the responses of a "trauma bonding", which some clients are susceptible to becauase of previous unresolved trauma. Hence, a kind of catch-22 in going to therapy for that. And when under the spell of trauma bonding -- like Stockholm syndrome -- I think there is a legitimate question about how much a person's will is "free".

The problem -- as I know well -- is that when under the spell, or in the bind, one can't see it clearly.