He looked surprise, and he just nodded silently. Well. He hadn't seen that one coming. But in his mind, it didn't really change anything; he certainly wasn't going to treat her any differently because of this. He did find it a little off-putting that it took something as extreme as finding out that she wasn't who she thought she was to re-evaluate herself, but then again, the reason didn't matter; she wanted to change, and that was the important part.
"Do your friends know yet?" But while he didn't care one way or the other about blood, he could understand why this would be such a big issue to her. She was a Slytherin, where blood was still incredibly important, and he doubted that people like Pansy would take well to this news about her.
"Blood shouldn't mean anything. If that makes anyone change their mind about you, then they really weren't your friend to begin with and you're better off without them."