In my book review of The Others Within Us, I wrote:

[An Internal Family Systems session] isn’t supposed to be just the therapist walking you through guided imagery, or you making up a story you tell yourself. The therapist asks you “Look inside until you find the part that’s sabotaging your relationship”, and you are supposed to discover - not invent, discover - that your unconscious gives it the form of a snake called Sabby. And you are supposed to hear as in a trance - again, not invent - Sabby telling you that she’s been protecting you from heartbreak since your last breakup. When you bargain with Sabby, it’s a two-way negotiation. You learn - not decide - whether or not Sabby agrees to any given bargain. According to Internal Family Systems (which descends from normal family systems, ie family therapy where the whole family is there at once and has to compromise with each other), all this stuff really is in your mind, waiting for an IFS therapist to discover it. When Carl Jung talked about interacting with the archetypes or whatever, he wasn’t being metaphorical. He literally meant “go into a trance that gives you a sort of waking lucid dream where you meet all this internal stuff”.

Some IFS therapists chimed in to say this was wrong. For example, DaystarEld:

https://www.astralcodexten.com/p/what-is-going-on-in-ifs