Hmmm. An older woman as a keyholder. A chastity cougar. I like it. The gals lewdly exposing themselves and demanding oral service are a special turn-on too. They are so direct, denying their slaves any delusions about what's going on and who's in charge.
I might look a bit more at older women ... I think their experience makes them more likely to be relentless keyholders ... and possibly of multiple victims.