Understanding the Perfect Punishment

There's a subbie I'm teasing long-distance... She can't get enough. She loves feeling so controlled and desperate. She rarely acts out, but I often threaten her with punishment just as a warning to give her best and put everything she's got into it. There's a great punishment I threaten her with that never fails to push herself into a subspace where she gives her all for me.

Spanking? She loves spankings! Further, she's submissive; she needs to please and serve. Experiencing a spanking as punishment would change the whole tone, the whole context, to something sad. If I think the idea of spanking her is hot, and if the idea of her being eager for it is hot for both of us, why would I want to taint spankings by associating that with punishment in her memory?

Denial? The aching, the pulsing, the wetness, the constant struggle to not squirm in her chair during the day... that's what she craves. That is what she gets for being such an obedient slut for me. Great, mind-crashing orgasms isn't the goal, denial is. Being teased to the point where she's begging, breathless, sometimes even in tears, is why she sought me out. This isn't punishment, this is the reward.

Pain? As I see it there are three 'levels' of pain in (my concept of) a healthy D/s relationship...

• The mildest is merely 'intense stimulation' that is pleasurable.
• The middle is pain that's so intense that it's not enjoyable but is endured for the dominant. Doing this well can bring us both closer, and is good for deepening her discipline and bring out her subbie nature, but it's still a "good thing" that I won't want associated with my displeasure.
• The third level of pain gets into "consensual non-consent". I'd be willing to start going there with her but, long distance, the risks skyrocket both in probability and impact: Even if I were to cause pain through hypnosis instead of real stimuli, chances that the submissive might go to a bad mental space rise, and long distance aftercare doesn't work well enough.

No, instead, I threaten her with orgasms. One per day for a week. It's not orgasm denial, it's a much more insidious form of denial - denial of that hot, tense, needy feeling that she craves to live and breathe. The idea of doing it doesn't arouse her (a sign of a great punishment), nor does it arouse me (another sign of a great punishment), but the reason she gets so aroused when I threaten her with it is that it proves, more than anything else, that I've got her number and I know it's the perfect punishment. Anyone not into teasing and denial would think this is a silly punishment, and her reaction to the threat inescapably reinforces that she's a true denial slut. It connects us... it proves that I understand this side of her much more than she's comfortable with and that not only have I got her by the clit, I've also got her by the part of her brain that keeps dragging her down the rabbit hole, taunting that part of her with the keys to getting out to run and play, a dog owner holding a leash & frisbee and asking "Do you want to go outside?"

Do you?