I felt it strange that she killed the captor as well.. All of his established motives throughout the episode seemed pretty clear up until the end:
1) He rescued her from the crash site while she was unconscious, using the rationale that she would have died/been eaten if someone else had found her first...
- This sets up fairly clearly that he was trying to do the right thing from the get-go. He didn't torture or rape or eat or do any harm to her here, he basically gave her shelter in a safe space (off the ground, in an apartment)
- His first lines in the episode are "You must be hungry", "My name is drogen, you are very lucky I found you. You're the only one i found in the wreckage"
2) He brought her food and told her to eat, since food is a scarcity around here, he gave her a fairly hefty portion and could have easily made her starve.
- Again, further solidifying that he's trying to help her or at least keep her strong / away from death.
- "its a safe place, I told you, you're in a safe place." -- "You haven't eaten", "Food is scarce, don't waste it."
3) She prompted him with requests to let her out to find her kids, saying that they could be in danger. He already knows this because
- "No one survives out there for long"
"It won't matter, there was a war, the enemy put poloxis in the water supply, a biological weapon, millions were killed. A few survived, but many are sick, despeate, violent. They've resorted to canibalism"
- From his perspective, they're already dead. Why let her out and risk her dying too? He said he was one of the only who prepared for the coming war, he has food, water, weapons.. He's basically the equivalent to the people in the US who have fallout shelters.
- When the doctor pressed for release saying she could find a cure, he said "there is no cure" -- from his perspective, the knowledge he has, this is true TO HIM. There is no cure. Why would he believe a random alien?
- "I'm your only hope for survival" -- further reinforcing that he has saved her and is keeping her captive (for now) in a safe place
4) When she hurt herself, he came running asking "What happened?" -- She then requested her medication, she played on the fact that he was alone, touching his hand and basically implying that she might get with him if he retrieves her medicine.
- He goes and gets the medicine. Whether his lonliness had taken over at this point, or simply his willingness to help, is unclear.
- This was his last interaction with her before she murdered him.
5) When he returns with the medicine, he is unarmed (well, he had a weapon, but it was not drawn), has zero intent or motive to harm her, yet the doctor stabs him. SHE takes the first strike.
- it is only after this point where he becomes violent. This person he's seemingly helped and kept in safety then steals his weapon, and while yes, he charged at her (self defense!), she shoots and kills him.
If you were the 'captor', and you found an unconscious alien life form that also had a weapon on her, and brought her back to safety, would you not lock her in a safe space until you determined her motives and her intent? Yes, it's perceived by the viewer as her being imprisoned, but how many of you would willingly trust a stranger, especially in a war-torn post-apocalyptic scenario blindly?
From his perspective, and rightfully so, he went out of his way to rescue a crash victim, keep her safe, fed, and healthy (agreeing to go out and risk getting her medication), only to be murdered by the person he rescued.
The doctor straight up killed a dude.. I get she did it out of fear, but as a viewer, she was not morally in the right.