Scene: The scene would take place a couple months after the final battle. Selene Riddle is the secret daughter of Lord Voldemort that stemed from a short steamy affair he had with one of his deatheaters. All her life she was kept in secret. No one knew of her, not even those of Voldemort's inner circle. He eventually made her into one of his horcruxes. He taught he all he knew. She lived under his shadow wanting nothing but to be like him. When her mother tried to take her away from the deatheater life, Voldemort sent her on a mission with every intention of her not coming back, alive.
After the big battle and Potter and his friends defeated Voldemort. Or did they? After all, in order to defeat Voldemort you have to destroy all his horcruxes. And no one knew Selene was one, hell, no one even knew Selene even existed. So perhaps Voldemort was just waiting within the in between awaiting for his reign to come again.
After her fathers death that's when Selene stepped forward and made herself known. Taking her place where her father once stood. As the new Dark Lord...ermmm...Lady. But one night she gets a visit from a deatheater that not only was he extremely close to her father, but everyone assumed he had died in the boathouse at the time of the battle. Severus Snape survived Nagini's poisonous bite. And now that he was back to full strength again he was pissed at what Voldemort tried to do.
Severus goes to confront the Dark Lord but instead is confronted with a woman he's never met before. But something about her is familiar. Is it the bitchy attitude she seems to hold? Or the cold dead look that's in her eyes that give it away. Selene thinks Severus betrayed her father and that's why he ended up dead. So she chooses to take her anger out on him. But he finds out she is Voldemort's daughter, and he was determined to get his revenge for Voldemort trying to kill him. Since Voldemort was dead, he settles upon the next best thing, his spawn. Thats when there seems to be a power struggle between the two. But Severus was older, wiser, stronger, and more powerful. Will he be able to tame the Dark Lords spawn?