To truly appreciate pain, specifically pain given or received as a form of or an addition to pleasure, one must first fully explore and thoroughly examine pleasure.
Pleasure and pain are simple responses to stimuli. But as thinking beings we have the ability to move between the two states fluidly and, With practice, substitute one with the other.
Most often this is done to transfer pain to pleasure but once you’ve gone far enough in that direction there is the desire to take pleasure and form it into pain. For the novelty, if nothing else.
I’ve yet to successfully do that. Though the results of the attempts is a delightful crippling of my ability to distinguish sensation itself as something other than a heightened mingling of pain as pleasure.
Pelgris 