Living with Pain as a Companion
There is a stark difference from:
being punished for doing wrong and as a part of corrective training, and
living as sadist and masochist, where it is the apex of the relationship.
There are Dons who fall into to trap of punishing submissives only for misdeeds or as a part of corrective training. This limits both the Dominant and the submissive for experiencing and enjoying pain for its purest of experiences. While punishments are effective to correct as misdemeanours and alter behaviour or counter bad habits, the trap is that many submissive who actually harbour masochistic needs will continue doing wrongs merely to receive punishments. Find non-physical punishments (such as corner time, caging, or shunning) as alternatives to the crop or whip. Make the clear distinction between what is a punishment activity and what is a fetish one.
If Pain is the Point
I truly prefer to be upfront with the submissive about my fetish needs so misleading them to allow for situations to occur where I can get pleasure is counter to every fibre of my being. The Dom harbouring Sadistic tendencies will make tasks and instructions increasing difficult to force the submissive into being punished. Both of these approaches are deceptive and eventually erode the relationship. Dom's who deliberate compel poor behaviour in a submissive if they are not a willing masochist will soon find the submissive looking for a change. The submissive seeking pain and not explaining this to the Dominant may find if they are uninterest in constant punishing soon tiring of the effort and actively disengaging from scenes. There are those that will crave the chance not only to suffer for the pleasure in it on behalf of both parties, and also excite in the physical expression of dominance through the delivery of pain. If PAIN is the POINT, then discuss it openly as a continued activity regardless of correction.
The Chemistry of Pain
Simply it is nothing more than chemistry, endorphins are released as a result of painful experiences properly tuned they become pleasurable. Stress and pain stimulate serotonin and melatonin production in the brain, transforming the painful experience into a pleasure. The release of epinephrine and norepinephrine in pain can also cause a pleasurable 'rush'. The pain-to-pleasure rush is, as we have observed over 40 years, a very addictive habit. Allowing and enabling the masochist to receive this addictive adrenaline rush that comes from the anticipation and participation in brutal punishment, is almost a mandate for true Dominants of a masochist. Equally then finding and partnering of masochist with Sadist make this situation far more simple and easier to enable.
The benefit is not only with the masochist find the pain will make butterflies dance in the stomach, intense endorphin rush at the fear of knowing expecting merciless punishment, it will arouse them sexual like no other aphrodisiac. Dominants and Sadist will experience the most intense desires to culminate the acts of violence with the sexual conquest of the equally eager victims. the sexperience becomes a win-win when match Sadists to masochists.
The Psychology of Non-Fulfilment
Masochist deprived of this natural high, like any other addict, will do anything to experience the high again. If trained to associate pain with wrongdoing they will continue simply to receive the pain. If they associate it as a reward, then they will maintain their best behaviour to avoid the corner and receive the lash. Any masochist who cannot find satisfaction with the current Dom will look to others, or worse start inflicts self-hurt upon themselves. And unlike the Dom, they will have no control, ever edging farther until too late they do something which is fatal. Just like the heroin addict who eventually ODs. Equally Sadist doms, who do not derive sufficient satisfaction form their submissive in accepting pain will look for others, if this has become a pair relationship, then very likely they will "cheat" on their sub merely to get their measure of the "rush" as well.
Another Reason for Poly
Not all people are into all things. Hence expanding options openly and honestly means that each gets their fulfilment without the others feeling denied or betrayed. Like an "Open Relationship" in the vanilla world, the "Poly Household" extends the conditions by which all parties can include others. Very stringent rules can be applied and expected followed without the "creeping about" so normal in vanilla relationships.