DS5 had number friends starting around 3 maybe? And there was a time when he also had state friends and planet friends, and all sorts of other things. For a while 19 was the main character among several numbers. They are mostly all girls and they can fly. Numbers like to eat poison ivy and salt and pepper. They also like rotten apples, and the only kind of fresh apples they eat are yellow ones. Then 6 showed up and became his best number friend and the others kind of faded away. Sometimes I hear about 9 because "She is always running out of purple paint." Last year, around the time that our baby was born, he married 6 (although he informs me they were married in 2009) and they have 3 children, Olivia, Quinn, and a baby, David. He and 6 both work at a hospital in Utah and she does surgery and he does anesthesia. They also run a Mexican restaurant in Little Rock. Recently they've also been taking pictures of objects in space. Last night he told DH, "6 is taking pictures of trans-Neptunian objects." Tonight at dinner he told me that "There is no dirt in Number World. There is only soil."
Needless to say, I'm fairly entertained by the things he comes up with. Sometimes it gives me insight into what he's thinking about. Sometimes it just seems totally wacky. When he was younger we would sometimes need to explain that he had number friends when he would say puzzling things to strangers. Lately he doesn't seem to talk about them much to other people. He has never demanded that I set an extra place for 6 or anything like that. It seems that all things that go along with her are imaginary as well. If he says something like we need to wait for 6, there is usually some solution that he can come up with on his own. Sometimes I have to prompt him: Can 6 take her own car? How will 6...etc. Occasionally he has told me that 6 is going to do some naughty thing and I say, well, what are you going to tell her to get her to stop? I can talk to 6, but I can't hear what she's saying, so he always has to deal with her himself.
Good luck with your black cat. I have a real one and he tries to lay on my head while I'm sleeping.
