Well I don't have an aggressive Roo but I have an aggressive Polish Hen, and its only with me, do you just watch her and see what happens. I have had to walk out of the pen backwards because she chases me, but she has never pecked at me or hurt anything. I don't know if its a female thing or if she is just that way. She is my youngest sons hen, so I hate to do anything to her, but she can be a royal Brat sometimes. She instigates the dogs to bark, but other than that, is pretty okay.