You can have a very intense relationship with fictional characters because they are in your own head.
I imagine them very clearly and then attempt to describe what I can see. Sometimes I draw them for my own amusement! (talking about her characters and scenes)
I can write anywhere. I made up the names of the characters on a sick bag while I was on an airplane. I told this to a group of kids and a boy said, "Ah, no, that's disgusting." And I said, "Well, I hadn't used the sick bag."
My readers have to work with me to create the experience. They have to bring their imaginations to the story. No one sees a book in the same way, no one sees the characters the same way. As a reader you imagine them in your own mind. So, together, as author and reader, we have both created the story.
I love inventing names, but I also collect unusual names, so that I can look through my notebook and choose one that suits a new character.
If there is a connection between Harry Potter and my new novel, it's my interest in characters.