QUICK UPDATE NOTE: I wrote this in an environment where I felt comfortable researching various definitions of Sadism/sadism and working off of memory of something I scanned a few days ago. I realize now most of the thorough definitions of Sadism/sadism are a little bit broader than I had based one section of this off of. Please bear with me on it as it doesn't really affect the overall result even if it does make me look like a bit of a jackass :)
I have served several Dommes over the years, a couple of which I would describe as "to their core" Sadists. The others exhibited sadistic tendencies or characteristics but the drive of their cruelty was not quite the same and during discussions about the topic, things didn't seem to resonate with them in the same way. After a lot of analyzing I have tried to find that dividing line between the two.
A common dictionary-like definition of a Sadist is someone that derives sexual pleasure from inflicting suffering on others. I'm not quite sure I like this definition as I tend to think of it a bit differently. I view sexual pleasure as: a physical act that contributes towards an orgasm and/or achieving said orgasm. Non-sexual sadistic acts do not supply this, but they still may give a sexual reaction in a Sadist. A person needs some basic factors to experience sexual pleasure:
-Being sexually aroused/horny (keeping in mind this happens at different rates for men and women).
-A mental and physical environment capable of sustaining the aroused state, ideally until orgasm.
So, re-written, a Sadist is someone that derives sustained sexual arousal from inflicting suffering on others. This definition makes a bit more sense to me based upon my experiences.
I have come to believe that one factor separating full Sadists from part Sadists is the need for active participation. Dommes that exhibit sadistic characteristics tend to require active participation to sustain sexual arousal. That is, they are turned on during play and will continue to be aroused on for the duration of the activities/environment. A full Sadist can achieve sustained arousal without being directly involved or present. The idea of the situation provides enough of a mental environment to continue the aroused Dom-space state.
This can be especially difficult to differentiate when dealing with a Domme's fetishes. e.g. if she is a bondage enthusiast, chastity enthusiast, etc. she may be able to fantasize about a situation without it being present and achieve arousal. How this differs from a Sadist is what factors drive her. The bondage enthusiast may enjoy the control, a sub's helplessness, etc. The Sadist may enjoy control, helplessness, but is driven by how the sub suffers because of it.
That focus on suffering tends to increase the natural creativity level of a Sadist. She doesn't just want to tie him up and immobilize him, she wants to bind him in discomfort. e.g. binding a sub in a sustainable/comfortable long-term position vs. an unsustainable/uncomfortable long-term position.
Another example would be locking a sub in a cage vs. locking him in a cage while gagged and blindfolded, wrists chained behind his back with the chain on the outside of the bars so his arms are pulled in an uncomfortable manner, spreader bar between his ankles and an anal plug while kneeling on dry rice. The latter situation requires a significant amount of extra work (probably at least 20 minutes as well as some awkward positions securing everything). A part Sadist may be fine with the just the cage but when she leaves the room, the arousing environment fades (or at least decreases). A full Sadist is more likely to go the extra mile but when she leaves the room, the juices will continue to flow.
Is that all necessary? No. It's a locked cage, he's not going anywhere. His freedom is gone and she holds the key. She does it because she wants to do it and enjoys doing it. The sub's suffering continues her aroused mental environment while she is now a passive participant. It is knowledge that keeps her going and not just fantasy. This fuels her creation of factors that will sustain arousal even after direct interaction ceases.
Another major factor that defines a full Sadist is the constantly evolving "one step worse than last time" tendency. Dusting the shelves? Let's add wrist cuffs and a chain. Next time it's a shorter chain. Next time it's no chain and just a lock binding them together. Next time it's locked behind the back. Next time it's locked behind the back with nipple clamps. Next time it's behind the back, nipple clamps, and a spreader bar, ball parachute, butt plug, bells (while being told to remain quiet) and so on. Eventually, dusting is impossible... so add a creatively harsh punishment for doing a poor job in order to maintain a sub's desperation level.
A part Sadist seems to find a point where it's "cruel enough," and reaches a plateau. A full Sadist seems to keep going and going and going with evolutionary time and creativity being the only limits (a sub's physical/mental limits seem to be forced to expand at the same rate).
I hope these differences between a full Sadist and part Sadist make sense.
These factors seem to be one of the hardest things to explain to a part Sadist since they don't naturally relate to them. It seems Dommes are either wired this way or they aren't.
It's sort of funny that I have met vanilla women that seem to exude many characteristics of fledgling Sadists. From what I can tell they get some form of endorphin "rush," but I don't think they have reached the point of a sexual connection. If you know the types they tend to seem somewhat playful and enjoy pointing out observations that draw attention to and embarrass men with teasing or jokes that border on being cruel. It makes me think they may have the wiring for this, but the likelihood of them entering the D/s lifestyle is still very slim.
One of my ex's was a Sadist whose evolution had been severely limited by the willingness of subs to suffer for her. I was the first that was willing to endure and I encouraged her to grow in whatever ways "did it" for her. A while ago I spoke with her for the first time in a few years and was a bit startled by how far she had grown (although it did not surprise me). When we were together we dabbled in chastity. Now she believed a sub should be in chastity 24-7 and released up to twice a year for an orgasm if their behavior earned it. She believed subs should be kept in wrist and ankle chains all the time, the heavier the better, and that they should move without letting them drag or make noise. She required subs to be on their knees whenever they were in the same room that she was in. She did not permit subs to look at her above the ankles or make eye contact. In the past she had loved to wear fur and went to great lengths pushing my sissification. She still loved to wear fur but now believed all subs should be kept naked and shivering (e.g. keeping AC cranked in summer and windows cracked in winter while she stayed bundled up). As of speaking to her she was beginning to explore pegging. It was not something she had done yet and the idea of it didn't really do it for her (as it does for most women who are enthusiasts), but she was searching for something to further degrade a sub and give them a twisted version of sexual intercourse now that she no longer permitted it by traditional means. I'm curious as to where she is now on this. Our relationship ended due to her having to relocate due to family issues and the offer for me to relocate with her was never extended. I'm also curious as to where I would be now if things had continued.