Marek couldn't keep his expression from revealing that the chair had hurt him, at least for a brief moment, but by the time he'd caught his balance, his glare was back. He wanted to retaliate, but that would be giving her what she wanted. He couldn't really compose his expression properly into the grin he wanted to give her, since the best defense against her attempts to provoke him was not to get angry, but he did manage a shrug.
"At least we'll be going down together," he said, almost managing to sound cheerful, even though his tone didn't match his expression. He picked his textbook up off the table and moved to leave the library. If she wanted to continue coming after him and attacking him, he wasn't going to fight back.