You start off alone in a facility, and she's your one voice of comfort. You grow to rely on her; you grow to trust her because she's all you have. You're all alone and the voice is your only friend in the world.
You trust her completely and accept every word she says as you navigate the test chambers. You're a little worried about the new consequence for failure in test chamber seven, but reassured when she tells you that you aren't in any real danger. Lying is part of test chamber nine, but you know it's only part of the required protocol.
It's in test chamber sixteen when your trust is truly shaken. You wanted to do your best for the voice, so you tried extra hard in the chamber "designed for military androids," but it wasn't good enough. When the first bullet hit your side, sending blinding pain through your body and your blood against the wall, you couldn't believe it. What happened to danger only being an element of the test?
Shaken, you manage to stumble through the rest of the chamber, constantly trying to make excuses for the voice, but as much as you want to convince yourself that she'd been mistaken on accident, you can't quite believe it. The discovery of what looks like an abandoned hiding place doesn't help either.
In the next chamber she regains your trust by giving you a new confidante and loses it just as quickly. You spend two hours curled up on the chamber floor, staring at the cube, wondering why she's doing this to you, wondering why she's forcing you to murder your new friend.
Is it because she knows you trust it more than her?
By the time you reach test chamber nineteen and you're on a moving platform sliding into oblivion, you can't make excuses anymore. You trusted her and she lied to you and she's trying to fucking kill you and three chambers ago, you would have stayed on the platform. You would have believed her and you would have gone to your death without even the slightest shred of doubt.
But you know better now. You're angry and you're furious and it tears at your heartstrings to hear her begging you to come back but you know she's lying. You know she's trying to kill you now and you know she always was.
It's you or her and you intend to be the one who makes it out alive.