Ghosts of Your Past

When you attended Hogwarts as child you, Severus Snape, & Lily Evans were the best of friends- that was until Snape called Lily a mudblood, and your friendship came crashing down around you. You haven't spoke to Severus Snape since that day, but now here you are the new DADA professor confronted with not only by your new teaching position but ghosts of your past.