We can't expect a person to be nice if we are nice to them.
...
Aaron didn't want Aarvi to witness anything more that could recall her days and bring the nightmares back.
Even though Aarvi wasn't pessimistic, Aaron didn't want a thought of 'Because of me.' to appear in her head. He never blamed her, he hoped she could not have such a mind.
Hence he cued Roach to wait for the interrogation as those things won't solve in nice talk and often need to be physically torturous. They weren't Aarvi to have a set-out plan and creep out the plan in her ways.
Hence Roach was waiting for Aarvi and Aaron to leave. Roach could guess it might be because of Aarvi as he was well aware of her past, even though he doesn't know the story.
