" Kill me then,' panted Harry, who felt no fear at all, but only rage and contempt. 'Kill me like you killed him, you coward-'

DON'T-' screamed Snape, and his face was suddenly demented, inhuman, as though he was in as much pain as the yelping, howling dog stuck in the house behind them- 'CALL ME A COWARD! "

― J.K. Rowling , Harry Potter and the Half-Blood Prince (Harry Potter, #6)