What is the theme in Sisters of Isis: The Summoning by Lynne Ewing?

friendship is a major theme in the book. Sudi, Meri and Dalila are three girls who do not know each other until they meet through Abdel and although their fates are forever tied together, they would not be likely to be friends under other circumstances. While all three are of similar age and live in Washington, D.C. their backgrounds are vastly different. Meri is the daughter of a Senator who plans to run for President. She has drivers who take her from place to place and bodyguards who go everywhere with her. She attends an exclusive private school while Sudi goes to public school and Dalila is taught by her uncle. Sudi has long blonde hair while Meri is tomboyish and Dalila shaves her head and wears unusual clothing.