For a second, Roger thought she was going to laugh. And then he might have had a reaction that might have been a little loud, but thankfully for the both of them, she put on a more serious face.
This wasn't a laughing matter!
"First off, what kind of Ravenclaw are you for applauding good decisions made by the other houses' quidditch teams? Second? Don't change the subject." Yes, a lot of his reaction had to do house prejudices. But he was also concerned for her. Times weren't good for Muggleborns and with all these decrees going around, Slytherins weren't to be trusted.
Rubbing his temples, he closed his eyes and asked in a tightly controlled voice, "How do you know he's different?" Roger was certain he didn't have to tell her that he didn't approve of her telling this Vaisey character about her blood status.