Hmmm. "A week or so?" Ella said thoughtfully. But there weren't many days left until the end of the the term, and Ella didn't exactly want to remember Carter going over to the 'dark side,' even if it was just a bet. Because, well, deep down inside she didn't really like all those Slytherins around Carter..

"Or you could stay at it for just a couple days," she added hastily. "Your choice." And she thought about the requirements in her head while he decided how long he'd keep at it.