In an interview with Joshua Jackson, he describes his characters's father, Walter Bishop, as the Wizard of Oz and describes their relationship. Joshua goes on to say what we can expect when the show returns on April 7.
Peter: Hello. Walter is that you? I can hear you breathing. Janitor: Is this Peter Bishop? Peter: Yes. Janitor: I'm calling from NY. I know this is going to sound crazy but I just saw a woman disappear in front of my eyes. Peter: Who is this? Janitor: Her name was Olivia. She has a message for you; she's trapped in the other universe