Dominique was trying really hard not to get attached to Elena. She did so rather quickly generally, but at this point it was much to her dissatisfaction and pain. But Elena was likable and couldn't help but endear herself to Dominique. It wouldn't hurt to be friendly with Sirius' roommate.
"Well if we ate it now, we might. But I don't know. Don't tell him I said so, but he's a bit clever. If we taught him, I'm sure he'd be almost as good as we are." She accepted the alcohol with a word of thanks. "It's quite alright. I've almost gotten used to Muggle alcohol at this point."