Draco blinked at her reply, pressing his hand faintly against hers. "I know. But I was one of the worst while we were there. And I was especially horrible to you because I thought you shouldn't have been possible and you were the person proving everything I believed in wrong."

He shrugged, clearly changing the subject as he pulled a black steel runic device out of a pocket that appeared to be empty. "Anyway. This is a child's toy that turns one sequence of lights into another in whatever way you tell it to; the lights go in there and come out there. And you can see the sequences down the side. Have a play." He smiled. "Just a weird child's toy for when the only spell a pureblood can cast is Lumos and they want to do more." He paused. "Until you start mixing it with fibre optic cables."