Harry went to the girl while Susan took care of the idiots masquerading as Dark Wizards. It was clear from the setup that they actually had no idea what they were doing, but steps had ot be taken to clear the area of any residual Dark Magic. He started with the girl, casting several detection charms, and was relieved when they all came back negative. They must not have gotten to that point in the ritual.
"You're okay," he soothed, easing her down from the platform and conjuring a robe to put over her. "We'll get you home as soon as we can, but we're going to need to go to the Ministry and ask you some questions. Then we'll get you home to your father." He used the same sort of soothing tone he used on other victims of Dark crimes, wanting to put her at ease as quickly as possible.
The girl gave him the same sort of disgusted look that Susan was giving the criminals. "Don't coddle me, Potter. I know how this works. Can we go now?" She crossed her arms, and Harry took a step back. Well, it appeared that nothing tonight was going as expected. The girl was tapping her foot impatiently, and bouncing back from this far quicker than Harry had expected. He looked over at Susan, wondering if she was thinking what he was thinking.