SARAH REES BRENNAN grew up in Ireland and then moved to New York and London, where she wrote her first book, The Demon's Lexicon. She never had an imaginary friend as a child, but she returned to Ireland to write about all the imaginary friends she has now and hopes you like them. Visit her at sarahreesbrennan.com or follow her on Twitter at @sarahreesbrenna, where they cruelly stole her last "n" and she will have vengeance.