He grinned, and leaned closer just slightly. Enough to be able to whisper in her ear. "Well, now you do." He beamed at her. "And I can teach you Quidditch if you want. If it ever becomes allowed again." Not that he would have any problem sneaking her out and teaching her clandestinely, but her father was a professor, and also knew his mother, and he valued his lie.
He grinned at her again, and tucked a piece of hair behind her ears. It felt really silky. "I'd like that," he said, and then pulled back. They had an adventure to go on.
"Right, this way," he said. He'd noticed her legs, which were very shapely and long, even though her head barely came to his shoulders. He led her very quietly out of the library, and they headed down the hall. "See, these portraits have gone for tea, we should make a note of that. They go every day at this time, up to visit the Fat Lady at Gryffindor Tower."