I am 15 years old, and I have full conversations with myself when I think I'm alone. I pretend that my favourite fictional characters are in the room with me, just hanging out or watching movies/playing games with me, and I will pretend that I am chatting to them about the stuff that's happened in my day and stuff I find funny. I've been doing this for a good four years now, and sometimes I'll be in the middle of a full conversation and somebody will catch me. I don't know if this is normal or not, and I don't know how to stop it.