Christopher Vogler writes about starting your story in the "ordinary world" of the protagonist, to show where he/she starts the journey.
This can be done on a"macro-level as well as the scene level, showing the "comfort" which actually sets up for the "conflict."
Example: In Grant Sutherland's Diplomatic Immunity, the main character Sam's daughter is shown first barging into his office at the UN (she works as a guide there) so she can eat her lunch in private (and probably so she can connect with him). She's a bright, funny, somewhat cocky 18-year-old, snarking at her old dad and making him feel both annoyed and gratified that she's deigned to share this time with him. (That's a good description of the relations of parents with their newly adult children-- annoyance and gratification.) While there's some tension in her sudden appearance (Sam is trying to investigate a murder, and he doesn't want her to know), their relationship is shown as comfortable, loving, and pretty easy. There! We can feel nice and safe, right?
But the point of providing the comfort is to set up the conflict. And this comfortable scene does. There's the tension of the moment (Sam trying to keep the murder from her), and also lingering past tension, right there in the middle of the tension. He focuses on her "lunch," a carton of yogurt, and can't help but make the observation that he hopes she's eating more than that. That lets the author slip in the information that Rachel (after her mother's death) became anorexic and almost died of starvation, and that though she thinks of herself as fully recovered, he never has gotten over his fear that she won't eat enough. So in establishing the comfort, the happy healthy daughter who barges into Dad's office to have lunch, he's also indicating the fragility of that comfort. It's built on a foundation of tension.
And the reference to her past trauma sets up for the next scene featuring Rachel. She is arrested for the murder and confined in a small basement room, and that's where Sam finds her. She's unconscious or asleep, and he's filled with terror. It's not so much fear of her being framed for this murder-- he's pretty sure he can make that go away-- but the memory of her near-death from anorexia, and the anxiety that this terrible experience will plunge her back into that.
We would not be able to experience vicariously his terror, I think, if we hadn't had that "other extreme" of comfort first.
Can you suggest ways of making the reversal more effective? Like putting a trauma after a scene that affirms the alternative? That is, let's say the reversal is that the protagonist learns that his beloved mentor has been lying to him. Would that be more or less effective right after a scene of him with the mentor, with much trust and admiration?