You had the same potion class as Severus, you never really noticed him being a, (whatever your chosen house is). He was always so snarky and honestly rude along with pompous. Though you couldn't deny it was impressive how smart he is.

You were close to failing potions and Professor Slughorn had asked Severus to be your tutor though he really hadn't have him a choice. So here you were sitting with him in the library as he prepared the ingredients for making liquid death potion.