Hermione had only recently noticed the good qualities of the new DADA teacher. She liked his no-nonsense attitude, his intense concentration, and his subtle good looks. She also admired his courage, the way he braved spying on Voldemort and the Death Eaters; she also admired the way he braved the criticism he received from students and collegues alike.

She got butterflies whenever she saw him now. Hermione avoided his gaze, and bit her lip with uncertainty when answering a question. She never knew how he would react. She kept hoping he would notice her.

Severus Snape happily noticed these things.