How can multiple personality be like a novel?

In yesterday’s post, I said that multiple personality is like a novel, with the alternate personalities’ being the characters.

Did I mean that multiple personality is faked, and that the alternate personalities are manufactured? No, I meant that, like multiple personality, novelists don’t create their characters: In the post before that, I had quoted Mark Twain as saying, “Writers don’t create characters.” And he did not merely mean they plagiarize from life. Twain said that he’s too lazy to create his characters, dialogue, and stories, so he waits for “the tank” to be filled up, and then he takes these things out of the tank and writes them down.

So how do people with multiple personality get their major alternate personalities, and how do writers get their major characters? Similarly, how do children get their imaginary companions? Only the brain knows for sure, and maybe, one day, neuroscientists will figure that out.