Bruce had heard that Wonder Woman was coming to his city. As Batman, he wasn't sure how he felt about it. While he'd seen enough of the heroine's exploits to know that she could handle herself, he still chafed at the idea of someone else coming in and thinking that they knew how things worked in his city. Of course, she might stick to her role as ambassador of peace and simply make her appearance at the gala and leave.
Once he'd learned that Diana would be at the gala, Bruce made a sizable donation to the cause to get himself on the guest list. It was a worthy cause anyway and he would have made the donation regardless. He just might have considered skipping the party. He certainly attended his fair share of both benefits and private parties-enough to keep up the Bruce Wayne persona that made headlines in tabloids across the country. That didn't mean that he took joy in such events. But it was all about keeping up appearances in order to keep his own secrets hidden.
The woman in question wasn't difficult to spot once he arrived. She stood out in any crowd. It went beyond beauty-he'd certainly seen his share of externally beautiful women. No, Diana had a radiance to her that hinted at an inner beauty. And if the press clippings were anything to go by, her ideals and bravery were admirable, if a little naive. He took a moment to admire the woman in question before he approached her. The crowds around Wonder Woman parted for him, as they usually did in Gotham.
He put on his best 'prince of Gotham' smile as he caught the woman's eye.
"Princess Diana. Welcome to Gotham. I'm Bruce Wayne." He favored her with a little bow.