Thicker than Water (Marauders Era)

They say blood is thicker than water. But they don't tell you its the blood of the covenant and the water of the womb.

Lavinia Selwyn is everything her parents ever wanted in a daughter. And she's never tried to be anything else. She's a poster-girl pureblood Slytherin who is in all the right crowds and making all the right friends from the moment she sets foot on the train to Hogwarts. She's top in her class and the envy of every girl at Hogwarts. But as pressure from her parents mounts, the disgusted stares of the other houses and the constant insults of the Marauders start to get to Lavinia and her perfect facade begins to crack. Before she knows it, she's struggling to function, practically screaming for help and no one seems to notice. Well. No one who would want to help her anyway. Sirius Black is the last person Lavinia would go to for help.