I am not an expert. I don't really understand why some people (including myself) find bondage and related pain to be an erotic, stimulating and desirable sensation.
Pain is the body's way of recognizing that damage is being done, or could potentially be done. It prompts action to avoid the pain, presumably removing the body from further damage. So why do some (including myself) seek it out?
I remember being fascinated with bondage when I was quite young. I knew nothing about it. I had never seen pictures, or heard comments. But I do remember being in my parent's garage at the age of 13, and taking down some rope and tying myself up. It was the oddest sensation, to do this and enjoy it.
The first time I engaged in real bondage as a sex act, I was 15. I actually suggested that my boyfriend use some rope to tie me up. He got some twine from the garage, and he tied me to the bed, using the twine to spread my arms and legs wide, over the side of the bed. In spite of the fact I quickly learned that twine is very rough and cuts in to the skin, it was an explosively erotic experience. At my urging, my boyfriend continued to help me experiment with techniques, some disastrous, and others marvelous.
Not all men are interested in dominating a woman. This seems like a complete oxymoron, but it is true. I found myself seeking boyfriends willing to tie me up. This proved difficult, as almost any guy thought he would enjoy tying a pretty girl up, and certainly was willing to try to get a chance at me. All too often, they were unable to take on the top role, and I ended up dumping some very nice guys.
When I was 18 and 19, I did some modeling, which included some fetish modeling. This introduced me to a whole new area of bondage; being introduced to real equipment, solid techniques, made me realize how far I had yet to go. I found myself growing excited that there was so much more to experiment with, new sensations and scenes to play with.
I have been very lucky to have a husband that has been willing and able to take me further. During this time, bondage has given way to experimenting with pain, a natural progression. Bondage is inherently uncomfortable. It is a very small step to the introduction of pain which excites me and makes me feel alive in a way I have never before experienced.
.... I have begun to desire pain in the same way I desire to be bound. It is an intense physical reminder of the loss of control, powerlessness, humiliation and subjugation. There is nothing which enforces the sense of helplessness than expressing pain by crying out, and having your cries ignored. Or worse, having your mouth gagged to suppress your cries, further removing control. Within the context of sexual arousal, I have found that my pain thresholds are increased. Pain becomes a part of the erotic situation. It causes, and becomes part of the arousal. I seek pain in the same way, and with the same passion, as I do sexual stimulation.
I seek out pain and humiliation now, and it has become an important part of my relationship; being a slave has freed me in ways that truly excite and satisfy me.
I still enjoy and prefer sex, simple, lustful sex with my partner. But life is all about variety, isn't it?