When Emily was five she had an imaginary friend. Usually when little kids create their imaginary friends they take the shape of a talking animal or another child. Emily's was different. He wore a bow tie. He had a big blue box called the TARDIS that was bigger on the inside and could travel anywhere in time or space. He'd visit for a while and then disappear for months at a time. When she was 12 he stopped visiting. She didn't see him again until she was a teenager. When she was seventeen, she ran away with him, leaving her old life behind, and she hasn't stopped running yet.