Fantastic. I'm a huge fan of redheads, in Silver you created the perfect character. Looking forward to more of both of them.
Which brings me to...more thoughts. While two beauties are certainly better than one, what (for me) brings out the "whole greater than sum of the parts" opinion requires that the two interact more. Here, Silver appears, has her part, then leaves before Parnell gets her turn. Both parts were great, but in future stories, to take it to the next level you might have them together either participating in, or at least sharing, the other's humiliation.
Additionally, you build up these stories fantastically, but then the climactic portion happens pretty fast, comparatively. Stretching it out some might help. It's a problem (how do you plausibly keep the situation going when any person would take steps to end it or escape given sufficient time?) I have too (though my primary problem is inability to finish any stories, which makes the other problems sorta moot), so it definitely jumps out at me.
Please take it as constructive criticism...you're definitely one of my current favorites here! Keep the stories coming