Blaise was there only because Astoria agreed to go with him, otherwise, he would have spent the entire night in the common room. Believing that pure bloods shouldn't dress up in costumes, he came one of his stylish tailor made suits with a tie that matched the color of Astoria's dress. He did his best to entertain Astoria, making sure that she didn't pay too much to Draco next to Pansy, which he did assume that she had taken interest in the blonde boy. Blaise is actually an excellent dancer, so when the Weird Sisters weren't playing on stage, he asked Astoria to dance and kept most of his attention on her. Every so often he wondered what sort of plans Daphne was off to, but not as much as everyone would think. He wouldn't have minded Draco cutting in for a dance with Astoria at all, wandering off to mingle with a few close acquaintances during that time. Blaise honestly had a better time at the ball with Astoria than he first would have realized, being his normal gentlemanly self around her. Once they were back in the common room, he would have kissed her without paying much attention, realizing it a few minutes later when he was out of her presence.