I created a throwaway account just to post here. I got here because your story was showcased in Kotaku by Kate Gray:
https://kotaku.com/blood-pact-does-sexy-succubus-bdsm-game-the-right-way-1836359...
Also, if it matters, I am a married white straight male.
*** SPOILERS FOLLOW ***
First things first: your story is delicious!
The setup in the library, getting me to know Alexa's character, is well done. It was cut a little short, and I wanted to know more about her, with more flavor about her personality. She almost passes as a generic character (maybe that was the intention, to make her a placeholder for the reader to project herself). But considering that knowing Alexa intimately was not the focus of the story, the setup didn't overstay its welcome and left me wanting for more, which is always a good sign.
On the other hand, the basement scene in the dark felt a little too rushed and didn't create enough engagement. It was Alexa entering the unknown, but it failed to build the feelings of fear, wonder and anxiety in the reader. Also, Emily is mentioned but is never reincorporated in the story (e.g.: Alexa realizing that the memory of Emily is slowly fading in the end), so it feels like a loose end. There are moments that the rule of "show, don't tell" is broken, that could've been better explored to increase the tension. An example is: "Alexa wondered if she had lost her sight. But she hadn’t."
Anyhow, it's the scenes with the goddess and the sex that really shine. They are very well written and got me really engaged! Every flavor missing from Alexa's personality is presented with gusto in Felanya. Her character being able to flow naturally from a jerk dom to a caring lover and back, while always displaying confidence and alphaness, was remarkably well transmitted. The intense contrast of Felanya and Alexa's personalities being portrayed, while at the same time they both identified with each other similarities, was top-notch and masterfully executed.
Here, the pacing of the story, the interplay between sex tension and dialog tension, growing and shrinking like an ever-rising wave, was spot on: the undressing, then reassurance; neck biting, then situation-questioning... on and on until it reaches the climax. Or at least I thought it was the climax: the aftercare in the middle of the scene took me completely by surprise... just for the action to pick up again, leading to the true climax, and ending the story decisively, leaving me yearning for more.
Even the no-excuse and slightly abrupt ending felt like being led by the no-bs attitude of Felanya, instead of being dragged down by the needs of explanations and whims of Alexa. Enticing, as it should be, giving space to my mind to wonder what's going to happen next.
Congratulations.