You refuse to deal.

"I will never make a deal with you! Leave now!" You command it. You sense the **** shifting. The hands come off your head, and hold you up by the waist instead and the cock slides down your chest. You feel breath on your ear, the voice giggles. It is definately female.
"Oh, are you sure?" You feel the long thing sliding out of your butt.
"Yes," you say in relief, "begone demon."
The voice giggles again. "I didn't get to be a succubus because I took 'no' for an answer, silly boy." You feel relief as you are lowered, but instead of feeling the couch beneath your butt, you feel the monster's cock. "I gave you a chance to do this the easy way," she whispers again into your ear before licking it.
She moans slightly as she forces the bulbous head into you. Now, your throat had never had anything go down it quite so large as this cock. A foot long with a bulbous head; while compared to a normal cock this is monstrous (your stretched throat can vouch for that), you were looking for something thicker for your butt. It is a good warmup though, like what you now guess is her tail was. She bottoms out easily and starts pumping you quickly. It feels good; the wide flair of her head catches on your hole each time, pulling on it pleasantly. The incorporeal succubus doesn't even realize you are enjoying yourself just as much as she is. Your precum drips through where she should be onto the floor below.
Halfway through, you start moving again; the succubus apparently takes a seat on the couch and takes you with her. As you lean forward to rest your head on the back of the couch, you feel the bottoms of her breasts surround your cock. She must be rather well-endowed. She inadvertently gives you a boob job as she continues fucking your ass.
When she is about to cum, you are too. You feel her cock swell and your ass tightens. She spews a massive load into you, and you cum onto Amy's couch. Just as your butt feels full of this inhuman quantity of cum, you are suddenly dropped onto the couch, satisfied. You rest until Amy walks in, completely nude and in much the same condition as you. From your position resting your head against the back of the couch, she can see your used butt leaking cum.
She crawls up and sits beside your head, then lifts her right leg over the back. You see both of her holes were used.
"So you didn't deal either? Was it a succubus too?" you finally query.
"Yes on both accounts," she sighs as she pulls you into a normal sitting position and plops herself onto your lap. "You have a bulge there," she notes as you point to her abdomen and note the same about her. "She did cum a lot."
A silence creeps over the room. You put one arm over her shoulder and the other on her upper thigh. "I have to confess, I asked for a life-changing encounter when creating my doll."
"I don't believe it! Me too!" She giggles. "I thought it would be in reference to the doll. I guess it was a general sort of question it asked."
"It was good sex, but not life-changing."
"Same here. So you really do like anal," Amy states.
"Well that was my first time, but yeah, I like it a lot. She had a huge bulbous head that kept catching as she pulled out. She stretched me out pretty well."
"Mine had two cocks. She asked me if I wanted to be like her. I was like 'Two cocks? What would I do with two cocks?' Well then she asked if I was sure and then she sure showed me what two cocks can do."
"That's how mine went, more or less. I think she was intending to hurt me, but was too busy fucking my butt to see I enjoyed it. We even switched positions."
"But I still wonder what was life-changing about it..."