I have my lone chicken in a run with my three ducks and they get along quite well, my run is long and has a small paddle pool at the far end and the coop at the other end so my chicken can choose if she wants to be near the water or not.
My coop is split level with an enclosed top with nesting boxes and perches that is accessable by ramp, and a semi enclosed space below. my chicken usually puts herself to bed up top,and my duckies go to bed on ground level.
I havent had any problems so far, nobody gets picked on, and during the day they all tend to stick together. While my chook scrathes in the dirt and straw, my ducks chill out in their pool. everybody is pretty happy.
One thing i did learn pretty quick is not to put much straw on the ground near the pool in the run, becoz boy does that chook luv to fling straw into the pool and clog it up so the ducks cant swim lol