All right. So you think they'll be able to go back into a larger flock as they grow? I just was starting to get worried about them being able to socialize with other chickens. I can't exactly have two chickens kept separate. I have the space, but I can't afford another coop or run.
Answer yes, in time, but not at first.
If you watch your flock you will notice that some birds hang with some but not others, and the aggressive ones will boss everyone and each other; there will be little "clicks' formed...sort of like high school.
Your Cochin and this other chick have formed "buddies," which is what you want...there is safety in numbers for those lower in the pecking order. These 2 will buddy together which will protect them from the other aggressive members in the flock and help them find peace within the flock.
In time, they will melt more into the flock, and may even eventually gravitate away from each other as they connect with other birds lower in the pecking order. [At one time I had 2 subgroups of 2 different chick broods but now everyone is well integrated...although the 2 youngest still hang together more times than not.]
But when you're ready to reintroduce the buddies into the main flock, don't put them into the flock in broad daylight throwing them in beak to beak. For a week or so let the flock see them with a wire partition in between so they are safe. You'll know when you should proceed to the next step as the flock will see them on the other side of the fence but not show any real interest or concern. Then at night put the two buddies together into the coop roost. If you can, put them next to several of your mild mannered hens. There may be some minor squawking and shuffling, but things settle down pretty well. In morning, there may be some minor scuffles, as the pecking order re-shuffles due to the new members, but the buddies will hang together and weather any "I'm boss and you're not" quick pecks.
Be sure to have enough elbow room for everyone. Always have some cubby holes and hiding places for the smaller birds to get cover that the bigger hens can't get into. A hen may chase them but they lose interest pretty fast when the younger ones are out of reach. If I had a chicken that was so blood thirsty as to be on a demolition mission against younger, smaller birds, I would remove her/him as that is too aggressive. Often putting the overly aggressive bird alone in isolation for a week and then reintroducing it into the flock knocks them down several notches in the pecking order, but be careful you don't make them the scapegoat everyone wants to attack when you reintroduce them solitarily or trigger their "Rambo" mode. If the hen/roo is still really aggressive, I get rid of it. (Dinner time!)
HTH
Lady of McCamley