Collider wrote...
People say that it's because Shepard did the Freedom's Progress mission successfully. But the game itself does not explain this. Miranda just suddenly becomes friendly for virtually no expressed reason.
See, I disagree. Freedom's Progress was Shepard's test, the one they planned on. Get him in the field, and see if his leadership skills are still there. Since he passed it, Miranda moved to phase 2: recruit Shepard to Cerberus.
I see her shift initially as a front - she is trying to tempt Shepard, and put a better spin on Cerberus. So she is more open to him, more
human, to give an approachable, attractive face to the evil entity. However, it did not work like that.
Both Miranda and TIM underestimated Shepard's ability to lead and influence his allies. Instead of recruiting him to Cerberus, Miranda got recruited away from Cerberus. It happens to nearly everyone that gets pulled into his radius.
The only exceptions I can really think of are Joker (same in both games), Engineer Adams, Kaiden Alenko, and Jacob Taylor. Nearly everyone else undergoes a shift, a realignment of their senses.