labelling Squeak

It seems like there was a very long time during which Nathan knew who we meant if we said somebody's name, but he did not label people. He labelled some favorite toys, foods and activities long before he labelled people. I cannot remember when he started to really talk about specific people when they weren't there. It has been quite a while that he will talk about our friend Lisa when she's not around, and he will in fact sing happy birthday to her in absentia. He will occasionally talk about peers when they are not around. If Daddy is sleeping and I've got the door closed, he will go try the door (he's not doing knobs yet, however) and say "kiss Daddy". He accepts the answer that we have to kiss daddy later, he's sleeping. The other day, his dad brought him home and then left again right away to go to the store. Nathan was confused by this and asked me "where's Daddy?" (like, hey, wasn't he right behind me?). And he definitely recognizes and labels his his sister. Nathan's dad tells me that Nathan identified himself in a picture ("Naynay") and said "Squeak" when shown a picture of his sister. On some of the rare occasions when his sister is napping peacefully in a bedroom and is not physically on my person, Nathan will ask me "Squeak?", and will accept the response that she is taking a nap and move on to something else. Sometimes if I am home alone with both kids I will nurse her on Nathan's bed while I put him down for a nap, and if I'm lucky they both go to sleep. The other day, Nathan's dad asked him if he was ready to take a nap. Nathan drifted away and came back a minute later. "Takennanap. Squeak?" Awww, Squeak is already taking a nap. You'll have to take yours without her. He does incidentally also understand her to be Cianna and will occasionally say "Cianna". I call her Squeak or Squeaky more often than I call her by her name though, and he has followed suit.