Causing Trouble

I have 2 chickens that just love to cause problems. They do not like the other chickens and just want to peck on them. I hate that they do that. These other chickens just want to roost and not be pecked. There is usually a lot of pecking and trading places and then it’s like they all calm down and sleep. They are so mean. They are old and they were here when we got here. I watched them for a long time the other night. It was ridiculous but they finally calmed down.