Chained to an Alter (NSFW)

You are an adventurer who just finished an lucrative job and heading down to the local tavern 5000 more gold than had before. At the tavern you meet an extraordinary beautiful man or woman who is absolutely charming. After a night of drinks and aggressive flirting you two go upstairs and engage in the most passionate intense love making ever experienced. That night you fall asleep on silk sheets, but in morning you find yourself naked strapped to an alter as the person from night before transforms into an incubus or succubus in front of you. They propose an offer: be their love slave and experience bliss 1000 times more than last night, or refuse and become devoured by their pack of devoted hell hounds.