Help identify this mystifying chick please!

[Little Jerry Seinfeld]

This little chick started out slow, much slower than the others, got him in a mixed batch of bantams at tractor supply, when his friends outgrew him I put him in with the younger bantams I had bought, then he quickly flourished and all of a sudden was huge! So maybe the other birds had been picking on him, though I never saw that. It could just be the others grew so much faster because they ended up being brahma bantams. Anyway I have searched and searched and can't seem to identify what he is, I'm sure it will be obvious to one of you seasoned chickeneers. I hope so anyway he is extremely muscular and has very tiny wings, he's about 4 to 5 weeks old and barely finally this week getting some real wings. I think the slow feathering is because he will be a rooster but we will see! Also has a very scant amount of feathers on his legs. Very full and fat bottom/belly/butt area, kind of like how a Cornish cross has a fat bottom/belly area.
So last week hey had another one that looked like him when he was a baby so I got her, she already has long wings, so I definitely think his slow feathering is because he's a rooster all the pics are of him, the last one is the new possible female, other than the wing difference he looked identical to her when he was a baby so I do think they are the same species. My local tractor supply uses the privet hatchery in Portales n.m. which has this entire list of

bantams. I looked up each one and still couldn't identify him!

 

[drumstick diva]

Please post new photos at 8 weeks of age. If it is a Brahma they are slow to develop.

 

[Little Jerry Seinfeld]

Ok I will, thanks.
[My other brahmas all look way different though, I have light and dark., about 15, various ages from 2 weeks to 7 weeks. (Unless of course I misidentified those!) This is the newest clear pic I have, it was when they were 3 or 4 weeks old, they are almost 2 months now and very full feathered. they match the pics for brahmas perfect now I just haven't got a good recent pic.]

If they are brahmas then I don't think these other two unknowns are. I'm kinda thinking they aren't on the hatcheries bantam list, maybe they are a full sized chicken that got mixed up... or could they be cochin bantams?
{Again this pic is of the ones I think are brahmas for comparison}

 

[Frazzemrat1]

That’s a dark brahma pullet, technically a different breed than a light brahma... if that’s what the other chick is. Are you saying they’re the same age?

 

[JedJackson]

I think the chick in the first four pictures is a light Brahma and the chick in the last photo is a white D'Uccle. They are clearly different breeds if you look at the wing coloring of both. Light Brahmas are not white but have the columbian color pattern-- white with black at the neck, wings and tail. White D'Uccle will be all white. The other, darker chick is a dark Brahma, and it is a completely different color pattern from the white.

 

[Crazy for Chickens!]

Silver Laced Cochin
Self Blue Cochin

 

[Little Jerry Seinfeld]

Thanks for your help!
I'm leaning toward thinking the unknowns are cochins too. Of course i thought the same thing about the ones that i think are brahmas now...maybe i just want them to be cochins haha!
These are my original ones I think are brahmas the 2ND to the last pic is of the one who is the same age as the unknown light one, I think he's a Brahma or cochin. It's just that the one I can't figure out what he is, is so different than the others, his wings are so small and he is so muscular.he's the last pic. all pics are from today

1. this one I call a brahma 7 or so weeks old I have 3 or 4 of these, one is kinda different looking.

2. this one I call a light brahma it is huge and fat 7 or so weeks old I have 2 of them both are much fatter than the first pics kind, bought them all the same day and got more and more chicken fever since then!

3. I think this is a dark brahma or black cochin. This one is the same age as the one I'm trying to figure out, which is this last pic, I will put him again since I have so many pics I've probably just caused confusion! The first post has better pics of him. I'm not sure exactly how old as I have bought so many bantams my "records" got confused.but I think they are 3.5 weeks old. I did buy them the same day along with some old English bantams that are much smaller than either.

Mr. Unknown today.

 

[Frazzemrat1]

The first one is a dark brahma and is feathering in as a pullet. Dark Brahmas are sexually dimorphic. The second is a light brahma and looks like a possible cockerel for now, since Brahmas mature slowly. The third is a Cochin, and a cockerel.

 

[Little Jerry Seinfeld]

I was thinking those three are what you said, thanks
it's the last one I can't figure out, leaning towards a cochin though it doesn't have the same body shape as the black one in the third pic... I will post more pics as he matures too.

 

[Little Jerry Seinfeld]

Are even the brahma bantams sexually dimorphic?
I agree that's what the first 3 are. I am leaning towards mr. Unknown being a cochin, but he looks so different than the black one.(third pic) I will have to post more pics as he gets bigger.
Thanks for everyone's input