Do we actually know how long Miranda was impersonating Mia? Like correct me if there’s something said in the game, or if there’s any official info about that, but I’m thinking… When Chris finds Mia, she’s wearing the exact same clothes as Miranda wore while impersonating her.
It’s the same even down to the shoes. Only the actual Mia looks dirty and a bit dishevelled, though not too much. Not enough to indicate she’s been in there for like, idk, weeks. I’m thinking that technically, it’s a different 3D model, as they had to change it a little by adding dirt on the clothes and messing up her hair a little.
What I’m saying is, unless they had reached their budget and just couldn’t spend any time making a different costume for Mia’s second model, I’m kinda drawing the conclusion that Miranda was only impersonating her for that day (because if they wanted to imply otherwise and had the budget/time/whatever, they could’ve had the actual Mia wear different clothes). It’s like she had Mia taken away and took her form by copying the exact clothes she wore that day so Ethan wouldn’t notice any difference, and it was that same night that Chris and his squad barged in.
And truly, from a narrative standpoint, it would make no sense for Miranda to spend too much time there. Her ultimate goal was getting Rose; testing Ethan was a secondary goal, and she couldn’t risk Ethan realizing. Note how from the beginning he’s already noticing stuff, like the creepy story (WHICH BY THE WAY, she stops at the point where the girl is trapped in the mirror. As she says that, she turns to look at Rose and stops narrating with the excuse that “she’s asleep”. I’m pretty sure though that she wouldn’t care to say the rest up to the bittersweet ending), the fact that she’s cooking a local recipe (she hasn’t gone fully native, Ethan, she is native), even how easily she says that things are going to be alright; in his diary, Ethan says that on February 6th, when he mentioned the events in Louisiana, Mia snapped at him. The first night of gameplay takes place on February 8th, and when Ethan talks about it again, “Mia” is just dismissing it as something that happened “so long ago”. All those three happened in the same evening, within at most ten minutes of gameplay. Miranda surely knew that the longer she stayed there, the bigger the chances Ethan would realize something was wrong.
Now I know Mia mentions she was used in experiments, but supposing Miranda took her early in the morning of the first day, Mia would’ve been a captive for almost 48 hours by the time Chris found her. That’s more than enough time to conduct some experiments, especially considering the complete lack of morality in how they were conducted.