"Somehow I'm not surprised," he said with a sigh. The simplest solution never, ever worked.

"Ordinarily I'd haul you off to my lab for a few weeks of experimentation on the energy transfer process -- huh, that sounded much more like innuendo than I had intended -- but I'm guessing that time is an issue here." Since she had attacked him and all. "So... please tell me you can time the draining process reasonably precisely, because otherwise I think the obvious answer is going to be very unhappy for me."