Ben was fairly good at cards, when no one was cheating (which was only about half the time, given the crowds he tended to hang around with), and he wasn't surprised at the outcome of the match. That being said, he'd been too focused on playful banter while they were playing to give much thought to what the outcome would be if he won. He'd jokingly talked about his brief career as a professional Quidditch player when she'd asked about his talents ("The ceiling in here might be a bit too low for that," was one of the tamest jokes; "I can find a snitch better than anybody; maybe I'll show you someday," was one he probably would have forgone had he not already had a good deal to drink). But since he'd won the bet...

Normally he would have suggested a Muggle place — remote, cheap, with no one from magical society to see them and speculate about an unmarried man and woman spending the night with each other, even if it was only dinner — but seeing her look of apprehension, Ben thought better of inviting her somewhere secluded. The last thing he wanted was to make anyone feel uncomfortable, deal or no deal.

Taking a step back from the flirtatious manner he'd worn most of the evening and keeping his tone merely playful, he suggested, "Maybe we can visit La Maison de Crouch and you can bring a friend. Introduce her to my brother." He would have mentioned her by name if he'd caught it, but if Miss Gallagher had ever specified he hadn't been paying enough attention to remember. He hadn't been thinking of that brief interruption during the card game at all, but now that the idea had occurred to him he really enjoyed the idea of forcing Aldous to interact with (and to be obstinantly polite to, as of course he would, being Aldous) such an obviously odious woman.

Obviously odious to Aldous because she was by no means conventionally attractive and because Aldous would likely be put off by her mannerisms, her career, and her poverty. Ben had no personal experience with her but was willing to believe she was a perfect pleasant human being (er, part human being), when she wasn't raving about his brother.