Parties were really Gatsby's thing, and yet he usually didn't like them. It felt different now that he wasn't always the one hosting, now that there weren't any expectations on him. And of course, it helped that the people here were much nicer, less judgemental, more accepting.
He was dressed in his own 20s fashions, as made him feel comfortable, and he was just enjoying the atmosphere. Drinking champagne, nibbling on the delicious food Cleo had laid out for them all.
"I say, this sure is a swell party," he said casually, just to the nearest guest who happened to be listening.