"Yes sir. I mean, no sir." As much as Theo would have expected the Professor to tell him when he needed to leave, he also felt that he'd rapidly outworn his welcome. Besides, sitting there and failing in front of the one person he actually cared about not failing in front of was like some kind of slow and outdrawn self-flagellation. Theo may have been a masochist, but even he couldn't take that kind of emotional torture. "Thank you for allowing me some of your time." he said, curling the puzzle box back into the cloth before he stood up. "And thank you for your help." And crap, now he didn't know if he should just say bye and leave or wait to be dismissed... better the latter, more scorn from Snape was preferable to accidentally insulting the potions master.