In hindsight, the wish wasn't a good idea, because I didn't know how it would work. If swapping brains made the same thing happen that would happen if our brains were lifted out of the skull and transplanted, then I'd be in Sarah's body. But I was fairly lucky, because the stone knew better than to do that.
I found that nothing seemed to change. And Sarah continued walking along outside the window, without noticing anything, so I wasn't just Sarah thinking she was Jon, I really was Jon. The information that had been in my brain had not been swapped along with the brains, so I was using Sarah's brain but with my own mind inside it.
But it was still Sarah's brain. I suddenly felt myself wanting a cup of coffee, but I never drink coffee. Then I looked outside and saw Sarah meeting her boyfriend, and it occurred to me how cute he was. I didn't have a sudden desire to go cheerleading or to ignore Karyn because she hangs around with the wrong people, because those details depend on exactly what Sarah knows and experienced, but I did feel a little feminine, somehow....