Ask him to take a photo of it (most cell phones have cameras) so he can show you. Then you can download and post the photo and we'll help. Realize that breed and variety are not the same, which I think may be confusing you. Bantie is simply a nickname for bantam. However, most folks who refer to them as "banties" either have mixed breed chickens or OEGB (not show birds, or they would almost certainly use correct terminology).
Variety is the colour/colour pattern of the bird, and almost never has anything to do with the breed, I will say that chickens cannot be peacock blue unless they are dyed. They do not have the pigments for true blues and greens. So, is it possible that the bird is not a chicken?
Whether or not a bantam will get along with largefowl depends on the individual temperaments for the most part, and slightly on the breeds involved. Laid-back largefowl will probably be okay with a much smaller bird. Flighty or bird-aggressive ones will likely not. A too-submissive bantam wouldn't likely fare well with them, either.
