My Stepmom Is a Vampire
Our Mc's drunk dad married a rich widow [who is his girlfriend's mom], and instantly his girlfriend became his stepsister. Things got twisted when he found out the widow and her daughter are vampires and are searching for a rare bloodline to increase their power. And consequently, that is happening to be our MC.
Tags: Ma/Fa, Consensual, Romantic, Fiction, Vampires, Harem, Polygamy/Polyamory, Big Breasts, Slow