A Merciless Affection by Verity Brown07/13/2015
When a N.E.W.T. Potions field trip goes badly wrong, a chain of events is set in motion that may cost Snape more than his life, and a student more than her heart. Angst/angsty romance. SS/OC (of-age student). AU after HBP but canon with OotP. Contains mature theme and some sex.