Excellent advice, I'll be trying this with a langshan. Don't know if it's a breed thing but he's definitely timid. His cockerel flockmate seems to be going out of his way to harass him. Honestly, Im afraid the langshan will hurt himself trying to get away. I'm sure hormones are playing a role but it's worth a shot. The bully has overall improved since being added to this coop and separated from his brother. He just has it out for this poor lanshan

. Although I prefer thinking of it as "Chicken Rehab Center" over "Chicken Jail" for spoiled little birds.
You may not have room in your run to temporarily fence off one corner, but you might be able to find a corner in the coop for it. Or perhaps you've been meaning to expand your run and just need some motivation. This is a good time to take a look at your setup and think about pushing out a fence to make 100 more square feet of space to make your flock happier. In a pinch, a dog crate large enough for the bully victim to stand up in can serve as a safe refuge during bully victim treatment. It only needs to be used during the day as the victim will roost with the others at night.