"Rogue then." He responded congenially. "Please come in." The old doctor stepped away from the door, aware in his own way of her nervousness. Never the type to force anyone to see him, he simply gave her the opportunity to come in under her own power and to shut the door if she saw fit to do so. If she was the type to be nervous enough to run, he didn't want to cut off her route of escape. It really wouldn't do so well if he did.
"What questions can I possibly answer for you?" No commitment in his response because he knew he didn't have all the answers. Instead, he would do his best to answer any questions thrown at him by what science he had at his disposal.