Luke has not yet officially become a thumb-sucker. In fact, it's looking more like he may be a 2-finger-sucker. Jack was a confirmed thumb-sucker by this age, but Luke just likes to suck/chew on any part of his hand. He will NOT take a pacifier, but there really are not many times that he seems to need "comfort measures".
Luke is a pretty content kid, as you would expect #4 to be. He likes to be up watching and squealing at the other kids, or whatever else is happening, but he is a good sleeper, and generally pretty happy as long as he is right in the middle of it all :) He has definitely found his voice and likes to be heard! He squeals more than I remember any of the others doing. It's very high-pitched and sometimes hard to tell, unless you can see his face, if it is happy or mad.
Luke lights up when he hears or sees one of the other kids (or daddy). His eyes get big and he cranes that neck around to find them when he hears them! It's so sweet. And although they are in his face a LITTLE less than they were at first (thank goodness, they were driving us both nuts), they still light up when they see him! Jack can be in the middle of a tantrum (pretty common lately) and see Luke and he just becomes an angel. I'm so thankful they all love him so much...so far at least. We'll see what happens when he starts crawling and getting into their stuff!