As I grew up, I continued to interact with invisible characters, giving them voices and personalities. It was a lot of fun. When the adults in my life let me know that having invisible friends was beneath my age level, and that I ought to grow up, I simply stopped inventing and talking to invisible characters in places where people could observe my so-called childish behavior. I would walk home from school rather than taking the bus, because it gave me more time for long conversations with invisible characters. Though walking was slower than the actual bus ride, when you added in the wait for the bus, it only took ten minutes longer for me to get home.
I never lost my imagination, and I continued to polish my skill at inventing and interacting with invisible characters.
As a writer, I simply invent a new set of characters, interact with them, interview them, and discover the most important, exciting, and pivotal moments of their life story. Then I write it down as they tell it to me. Yeah, that’s where my ideas really come from.