Aaron is taken aback by Katrina's question. He becomes nervous when he sees her face turn serious. How am I supposed to tell her that I know because I'm the man who raped her that night? No, I can't tell her right now!
From Katrina's silence, he feels that he is on thin ice. She must hate that man a lot. Who knows what damage I caused her all those years ago? But I didn't have any choice at that time, and if I didn't take her as an antidote, I might die immediately. I feel helpless that night and leave me with no option.
Something occurs to him. She must have changed careers because of what happened. Why else did she turn white when I mentioned it? Was my conclusion right? I caused big damage to her life, and I can't bear the guilt of seeing her like this.
Although Katrina doesn't look angry while she watches him intently, Aaron feels guilty and finds himself unable to look at her directly.