Some hens, like my japanese bantam, love any and all chicks. She will brood side by side with anyone, and even help them with their chicks if the other hen will let her. She will adopt any chicks I give her up to a week old (meaning she is fine with having chicks with a week in age difference and added a week after the first).
My bantam rocks are horrendous. They will kill anything, and because they are coparenting they will gang up on another hen, with one fighting the hen and distracting her so the other can kill the chicks. My third bantam rock is at the other end of the spectrum and she is so laid back that she often ignores her chick and she is not good about protecting it.
Out of 40+ hens I also have two non-broody types that will sometimes attack chicks. Everyone else ignores them, and my head hen will run to their aid if she hears them in distress. My roosters are all good with the babies.