How I Fucked My Archnemesis and Saved the World (F/F BDSM)

Superheroine smut! young, spunky superhero Leda breaks into supervillain Eve's HQ to bust a plot, only to find that the "plot" in question is a drug to make people addicted to pain. Our heroine gets a dose of this intoxicating drug, but luckily for her, Eve is testing her tolerance for pain in only the best and kinkiest ways possible. This erotic novella features BDSM of every stripe: paddling, flogging, knifeplay, breathplay, tit torture -- read at your own risk!

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Excerpt:

I hated her, I hated her, yet my heartbeat was quickening in anticipation. She picked up the flogger and began to swing it into my shoulders, with the same sting but more control. “I’m impressed,” she said casually, “that you figured out this experiment so quickly. You are a quick study.” The flogging picked up speed, and my flesh grew hot and throbbing under the sting of the leather tendrils.
“I know I said you would live,” she began, and my stomach contracted, “and go free after you have been of use to me. But if you stayed – “her flogging inched down my back methodically – “I’d have a lot to show you.” The innuendo hung on those words, tightening my stomach. My back felt like it was on fire, burning acute pain that focused every nerve of my body. I perversely enjoyed the throbbing and felt guilty for it.
She then switched to a circular motion, letting the leather fan down my spine rapidly. I arched my back, pulling away from the sensation, and Eve laughed. “You can’t do much about it.” To punctuate her statement, she picked up speed and strength of the flogging. I resigned myself and relaxed the tensed muscles in my back, leaning into the pain eventually.
The handkerchiefs in my mouth were drying out my palate as they restrained my tongue and I tried pushing them out of my mouth. Nothing. At least, nothing until they began to trigger my gag reflex, fuck. I gagged, and when Eve blithely went on flogging my hot, inflamed back, I threw the handkerchief in my hand as hard as I could muster.
She noticed. “What? You’re nowhere near done.” Still, she stopped and walked around to face me. “Ah.” She saw me gag on the handkerchiefs and tugged them loose. Better?” My eyes had watered when I’d gagged, leaving tear tracks down my cheeks. Eve laughed when she noticed, and kissed away each tear mockingly. I squeezed my eyes shut as her soft lips brushed my cheeks and my cunt tightened. I couldn’t feel this way about her, I couldn’t.
I felt her read my mind. “But you do,” she murmured against my cheek. “Like I said, we can fuck later.”
I couldn’t even protest at this point. I just nodded shortly because god, did I want it.