It is never revealed who or what the mysterious voice that Allie hears is. However, there have been several speculations and theories; for instance, many readers argue that the voice Allie hears is actually the voice of God, as the voice seems to know a lot about religion and talks to Allie the way God talked to Eve. Other theories claim that the voice is Allie herself, except wiser and more mature; Allie, essentially, communicates with herself on a subconscious level and thus guides herself through life.

There are also some readers who think that Allie has some kind of mental disorder, because the voice seems to have a 'conscience or a mind of its own.' The most common and most popular theory amongst the readers, however, claims that the voice Allie hears is the skein, as it is very powerful and exists not just as a part of the body but also as a part of the mind and the soul. The author leaves the nature and origin of the voice open to interpretation.