He should have known that it would be Cath and not Nora. Nora wouldn't do something to rash and hasty if she was angry. Especially not throw a couch.
Marc watched Cath, frowning and shaking his head. "I have no idea what you're saying. English." He got that the other was angry though, and likely anyone else would be scared, but Marc wasn't.
And really, if he had to guess, Marc would figure that Cath might be asking why he was an idiot. Or something along those lines, at least. "Put the couch back and you can shit talk me in English."