My son has changed so much in 4 months. Not in appearance, but in personality. Watching him now gives me so much joy. He interacts with each of us differently. With Zoe, he observes closely how she talks (usually on the phone) and laughs. He plays happily with Ashlee, she dangles toys for him to grab. With Hubby he laughs loudly, "Daddy" literally means fun to most kids. With me, he vocalizes constantly. While I read to him, he talks about the books with me (I think).
I miss him being a newborn, but I love how he's growing right before my eyes...chubby, bright-eyed, and breastfed!