Turning Tides- Snape's Sister (Marauder's Era)

Evelyn Snape is a werewolf. (Just don't tell anyone). She's also the twin of Severus and both are best friends with Lily Evans, the redheaded spitfire. When Evelyn finally gets the opportunity to attend Hogwarts her 5th year, she meets the four boys that have been the cause of Lily's ire for ages. None more so than James Potter.