Just add some ideas to what Sebastian suggested. These are pure roleplay suggestions.
It occurs to me that for her to become corrupt she has to have somebody to "do the corrupting" and an observer to recognize the extent of that corruption.
In this plan (which could span several weeks or months) you will play two distinct characters.
- A "Master Confessor"
- A "Corruptor"
You start the scenario with a "confession" scene. At this point she is relatively innocent, but she has started to have naughty thoughts. And she has met this guy (the Corruptor) who seems to want her to do even more naughty things. And this is what she confesses.
In the "confession" you're her Master Confessor. I think some degree of ceremony and ritual would be good. So when she confesses she would begin by saying something like...
"Forgive me, Master Confessor, for I have sinned."
I'm an atheist, so I don't know the ritual of the Catholic confession but it's certainly online somewhere and you can adapt it easly.
What I do know is that the process has three stages. Confession, Atonement, Forgiveness. This is pretty powerful stuff in a D/s context.
You listen to her confession and suggest an appropriate punishment. Begin with mild stuff because her sins are not too serious...yet.
So then a couple of days later you (playing her "Corrupter") call her up and you order her to do something naughty. You can take your pick - including Sebastian's suggestions. But these "sins" will "ramp up" over time to reinforce the impression of a process continuous corruption.
For example...
Step 1 is simple stuff, such as making her wear highly erotic lingerie under her everyday clothes. How about stockings, garter belt, and a proper lace-up corset? Maybe latex panties. Nobody else would know...except her Master Confessor when she tells him what she has been forced to do.
Step 2: She has to wear a butt plug. Or the latex panties you can buy with a built in dildo and butt plug. If she needs to go to the bathroom during the day she has to call her Corruptor to ask your permission to remove the plugs.
Step 3: Play act her being a prostitute. Except you (as her Corruptor) are the client. Make her wait in a bar and you "pick her up", and then maybe take her back to your car where she gives you a blow job. Make sure to pay her in cash.
How it goes from there is up to you both. But each time she commits one of these sins she has to confess them...and to be punished more and more vigorously by the Master Confessor. You could even ramp up the ritual aspects if you like.
I don't know how often you "play", but try to space out these sessions. By making her wear the lingeries under her day clothes for a week or so it will build the feeling of her continued corruption. I would suspect your everyday love making during the week would be enhanced too
Then at the end of that week she has her session with the Master Confessor. Then after she's forgiven the Corrupter just makes her do something even worse.
Does that make sense?
Cheers,
Stanley