I never felt that having mine service another man at my direction was anything more then her proving that she will do what I ask of her. Each time the friend didn't seem to feel that he had been dominated by me. He and she had an experience both enjoyed.

I have also shared a slave with a friend me giving her a pleasure spanking to start things off and when she is about to cum have her suck on his cock. The night takes off from there but the other male had to follow my rules and my lead.