I've only ever hung out with one other person who I knew had bipolar but we did get along very well. We never really fought since each of us was diagnosed and knew about each other that whenever we said or did anything rude, we knew not to take it personally. She however was taking medication and seemed far more stable than I was. One time she told me that I was scaring one of the new employees one and made me go home and it became a running joke between us. Since we were both bipolar, we had a unique relationship that wasn't harmed by the diagnoses. There was no blaming bp or being wary of how the other might react. It was one of the easiest friendships I've had.