I'm approximately a week early for the 6 months post, but I skipped 5 months completely, so, it all evens out.
At (almost) 6 months old, Caleb is a champion roller...from his tummy to his back. He will not spend any time on his tummy whatsoever, and instantly rolls onto his back whenever I try to have tummy time for him. He has fun rolling though, so I guess it's alright. He doesn't ever roll from his back to his tummy, I don't think he's interested in trying, though he does roll onto his side regularly.
He's sleeping in his crib alright now, although whether or not he is going to sleep for very long is a constant mystery. Sometimes he takes long naps, sometimes he sleeps for most of the night, and sometimes he wakes up frequently, and I have no idea what makes the difference.
He is still quite large for his age, fitting comfortably into 9-12 month clothes at the moment. He still looks completely bald, though he's got peach fuzz all over his head, it's fine and thin and pretty invisible unless you're really, really close. He's generally very smiley, and tends to grin with his mouth wide open and his tongue sticking out lately. He chews almost constantly on his fingers or his sleeves or my sleeves or anything he can get in his mouth. He drools a lot. No teeth yet, but I suspect they are well on their way.
He had a fever for a couple days a few weeks ago, and refused to eat any baby food for about a week and a half after that, but since then he has returned to being quite a good eater. The only thing he has tried so far that he obviously dislikes a lot is green beans.
Caleb has turned into a complete mama's boy. He cries after a couple minutes of anyone else holding him. He screams if someone else is holding him and he sees me (even if I'm right next to him). He dislikes it when I set him down unless I sit down right next to him and play with him. He's also fairly shy. He will smile giant smiles at other people, but usually buries his head in my shoulder after a few seconds of smiles.
He still adores watching Aiden, and for the most part they get along well. Aiden finds it hilarious when he makes him laugh, and tries to share with him regularly. He also screams, "Stop crying, Caleb!" when Caleb has been crying for awhile, particularly in the car. Occasionally he tries to play with him a little too roughly, but he's not hitting him with things nearly as often anymore. Watching Caleb chew on everything seems to have inspired Aiden to do the same, again, and he's been sticking all sorts of things in his mouth. Aiden particularly likes chewing for a few minutes on his old pacifiers.
I am hopeful that Caleb will learn how to sit up soon, so he can start riding in the cart at the store rather than me having to carry him in the baby carrier. And that he will consistently sleep longer. And that he will be willing to spend some time on his tummy soon.
Overall, he is a delight to have around (tiring, but delightful). Hooray for your half-birthday, kiddo!