One of the unexpected perks of the Battle of Hogwarts was that Hogwarts gained a few extra ghosts, seeing as so many people had died there. But what nobody was expecting was for Severus Snape to be among them. He was as bad tempered dead as he was alive, spending his time haunting the dungeons and Gryffindor tower, screaming at first years who were doing their potions homework wrong and also at any Potions professor Hogwarts dared to hire, telling them they were doing their job entirely incompetently.
He had a particular distaste for 'Potter's spawn', redheads and any child who even remotely resembled Neville Longbottom. There was one particular redheaded Potter, however, that Severus took a shine to, and that was Lily Luna. None of the other children would ever bully or tease her, because they quickly discovered that you'd be haunted by Snape in your sleep. Lily eventually came back to Hogwarts to teach Potions, and for the two decades she was there, the dungeons were at peace. One day, however, Lily slipped on the wet floor in Moaning Myrtle's bathroom, breaking her neck.
The accident was fatal. Even her parents had outlived her; and the hundreds of people and students who had known her mourned for many days. One morning, however, a second year Slytherin ran into the great hall screaming that she'd seen Professor Potter (Lily had never married) in the corridor, and sure enough, a ghostly Lily Luna floated in, accompanied by Snape. There was quite a round of applause, and when Harry heard, he cried.
And so it was that Lily and Severus haunted Hogwarts for many centuries to come, although Snape was a little more peaceful now he had found a Lily to love him, and one who would continue to do so for eternity.
Because seriously guys, Snape deserved a happy ending. Leave me a review if you enjoyed it :D ~Draco's Felix :)