This mistress was curious as to whether a guy with a tiny dick was able to wear a chastity device and whether it would be effective on him. And that is why she chose to try it on this guy because she knew that he had a small dick. The mistress had a great time making him wear the device and then trying to tease him and turn him on.
Mistress Deviant had a patient that she had been treating for some time. He had grown fond of her and she could tell he had a big dick which she missed as she worked long hours and did not have much of a social life. So the two of them found themselves fucking today as it was his last day and he was not well enough not to have anymore doctor visits.
This mistress was tired of having a baby daddy who had a hard time keeping it in his pants. And she had to find a way for him to change for the sake of her kid. So she went and bought a chastity device which she forced the guy to wear and then she dominated him with it. It was cruel for him but it taught him the manners that she needed to be taught.
This mistress had an errant slave and she did not want him to think that she was weak and she could not do anything to him. She disproved that by cock locking him. She took his dick and she caged it before she hid the key and he had to survive like that for a week. It was the longest week of his entire life and he changed to avoid further punishment and humiliation.