A wave of something like fear washed over River, and she felt her face growing hot.
She hadn't liked her time in Arkham. She did not want to go back. If they tried to make her, they would be very, very sorry.
River didn't like thinking about the Joker. Something about him made her very upset. She supposed that this was because, like anyone, if he thought about something often enough, she heard it. Loudly. River heard some truly disturbing Joker thoughts in her time. He made her very uncomfortable.
Listening to Hannibal explain the best line of thought, River felt her eyes growing hot with tears. Until the day she died, she would not accept that there was no logic here of any kind. There had to be. Her brain seemed unable to handle another possibility.
In another second, the frustration had taken over, and she was outright crying. River wasn't embarrassed, and would not have been even if she had control over her emotions like a 'normal' person. Her situation was awful.