Jennifer, Hecate, Macbeth, William Mckinley, and Me, Elizabeth — E.L. Konigsburg

"Witches never lose anything," said Jennifer. Almost true, Elizabeth decided, as she became Jennifer's apprentice witch. Before Jennifer, Elizabeth had been the loneliest only child in the whole U.S. of A. After Jennifer, there was no time to be lonely. There was only time for, among other things, learning to eat raw eggs, to cast short spells, and to get along with Jennifer. Best of all, Elizabeth had someone around who felt as she did about a lot of things. It was all great, until the day they started to make flying ointment.