This story is a memory from many years ago, I'm sure the details aren't perfect, but the general story is true. When I was a younger man, a young Dom, with barely 20 bucks in my pocket yet cocky with impunity, I dated a girl named Corina. She was a couple years younger but already a respected graphic design professional; she could have easily done better than me, but she was very submissive and I was a dominant that she trusted and made herself available to pretty much at my discretion. To this day I've never met a woman with more sensitive nipples. I've read porn where a woman can orgasm from only having her nipples touched, but Corina was the only woman I've ever seen this from in real life. I would sometimes just require her to stand with her hands behind her back or locked behind her head and just pinch and play with her nipples, touching nothing else, and she would come from it. When I first met her at the dance club I frequented (I was 21, she was an adult, but too young to be there) and walked her to her car, I thought it was going to be limited to a make-out / number exchange, but when I touched her nipple (outside her shirt and bra), she let out long exhale, began panting, and asked me to come back to her apartment. I obliged, we fucked on her bedroom floor, at one point I risked the trial spank, she melted, and I was her regular Dom soon after.
Her nipples would become so sensitive while we fucked that she had an odd dichotomy where she resisted them being touched, but if they were touched she would instantly orgasm. I would often be on top of her in missionary position, I would lean down to suck on her nipples, and she would push my head away and cover her tits with her arms. I would let her push me away two or three times for fun and then I would grab her wrists, hold her hands down by her side, tease her, and then aggressively suck on her nipples and she would explode into orgasm after orgasm to exhaustion.
One time (I'm paraphrasing as best I can remember), I was feeling particularly merciless. After whatever foreplay and doggie style, we got to missionary position and, as usual, she pushed my head away from her tits. This time I thrust all the way into her, held her hands up by her shoulders, leaned in and whispered in her ear, "I want to be very, very clear, and I need you to pay attention. Do I have your attention?"
"Yes, Master."
"Understand," I said in a very matter of fact tone, "that I'm going to suck your nipples, and I'm going to suck them viciously. I will be giving you no mercy, no break. I'm going to suck them with all my might, and there's nothing you can do about it. Are we clear?"