Most people might have mistaken this black-clad figure for Batman himself, as their costumes were similar. Batgirl, of course, was not most people. This newcomer's movements were very distinct from Batman's.
When he perched atop a stone gargoyle, Batgirl made her move. She emerged from the shadows, striding across the rooftop toward the black-clad figure. She didn't say anything. She just stared at him.