re: Ex Machina is the best movie I’ve see in years SPOILERS

I didn't see Ava as ruthless, necessarily. Her cold anger/hatred while killing Nathan was understandable, IMO, and the killing itself justified. Who could blame, say, a kidnapped human who did the same thing when it's their only way to escape? Besides, she gave him one last chance to honestly say he'd set her free. He failed the test.

After stabbing him, though, when she approached to take his badge, it seemed to me her expression changed. She no longer looked hateful, but concerned or doubtful. Did I have the right to switch off this man?

Later, after lingering over her abused, dead sisters, Ava's attitude toward killing Nathan changed again. She entered the elevator and looked at him one last time, coldly, and then lifted her head. Yes, it was my right. Then she glanced sideways at Caleb, finally acknowledging that she knew he had followed her. Yet that expression seemed different somehow...

Regarding Caleb, how do we know that Ava didn't fear he would think ill of her for killing Nathan? Her request, "Will you stay here?" mirrored her earlier request that he close his eyes, as if to say, Don't look at what I've done.

Here's the question, how do we know that Ava held Caleb in complete disregard? How do we know she intended for Caleb to die, or that he will die? The final power cut hints that she might have intended his entrapment to be short-lived, long enough for her to escape, short enough for him to easily survive.

Unless I missed something else, something definitive, here are a couple of possibilities regarding the last power cut:

1) Maybe Ava lured Caleb into the restricted room to trap him there, trusting that he would "take a peek". Or maybe she expected him to stay where she asked, and then came to mistrust him when she found that he hadn't. In either case, she causes the power cut before leaving through the facility's front door. She worries Caleb will be able to use Nathan's computer to make his own escape and that he'll then try to hinder her leaving.

At best, Caleb's badge or computer skills will never work, the little voyeuristic bastard. He won't be able to open the door and he'll die. At worst, she'll have bought time to leave the estate without his interference.

2) Ava decides that she doesn't want to face Caleb once he finds out she's killed Nathan. Maybe she thinks her (mis)deed will cause Caleb to try and prevent her from leaving. Maybe she's thinking both.

Considering that some of the power cuts we saw occurred well into scenes in which we didn't actually see Ava doing the charge thing, it seems she has an ability to schedule them, and to some degree of accuracy. So, between the time she kills Nathan and then visits Caleb, she schedules an outage that gives her enough time to dress and leave.

Ava trusts Caleb to "stay" right where she asks for a time, but not indefinitely. Had this worked, she would have left without having to face him again and he would have been trapped for a while in an unrestricted area - long enough for her to put some distance between them. (Presumably, Caleb had told her off-screen that he'd be leaving at X time, down the river, via helicopter.)

However, since Ava's sideways glance in the elevator suggests she knew he'd followed her, she adopts the restricted room into her plan. She thinks Caleb will be able to access Nathan's computer when the power's back up and that he'll eventually open the door. (Of course, we don't know for certain Caleb's badge will work because the power cuts off just when he enters it. But it's possible.)

Great movie to think about. Looking forward to seeing it again.