Try using Vicks Vapor Rub on the chicken that is getting pecked. I had the same problem when introducing a new hen and Vicks solved the problem. Now everyone in the coop is friends.
I have a hen the mates and lays eggs but the eggs seem unfertilized. The rooster I have mates with other hens and the eggs develop. This hen is a black Spanish game hen imported from Puerto Rico and is one year old. Does anyone have any suggestions?