This is what I think too. She's been scared and even frightened every time she came with Vargas; it's like she doesn't understand what is going on. In the last update, their physical compatibility rose with each orgasm, which is telling as much as the fact she found sex with her boyfriend not as nice.
As for Vargas caring... no clue. I think he feels like she's his equal in many ways, but what that means for him as a character, I don't know.
Every lie Luna feeds Aiden is hitting her, which is fun. I wonder what will happen next, moral Vargas-centred corruption, or something else, like needing to make a decision as Varga's lieutenant that Luna is willing to do to keep their cover, but Aiden finds morally wrong - something that makes them drift apart more mentally or emotionally. I don't think its time for more comparison between the two men physically, given the call in the recent update, which was really fun. That watch and the heartrate monitor is a neat way to make Aiden aware yet not of what's going on. Although also creepy.
Different clothing would be interesting. Luna and the gaurd needing to work together on a mission?
Oh, wouldn't like to see Luna think Aiden has something going on with the blonde gyaru. That kind of thing is overdone, and wouldn't feel right with her personality.