SPOILER ALERT – If you haven’t finished Harry Potter and the Half Blood Prince yet, you wouldn’t want to read what’s coming up.
Source: Harry Potter and the Half Blood Prince, by J.K.Rowling
And Harry realized, with a shock so huge it seemed to root him to the spot, that Malfoy was crying — actually crying — tears streaming down his pale face into the grimy basin. Malfoy gasped and gulped and then, with a great shudder, looked up into flu-cracked mirror and saw Harry staring at him over his shoulder.
Malfoy wheeled around, drawing his wand. Instinctively, Harry pulled out his own. Malfoy’s hex missed Harry by inches, shattering the lamp on the wall beside him; Harry threw himself sideways, thought Levicorpus! and flicked his wand, but Malfoy blocked the jinx and raised his wand for another —
“No! No! Stop it!” squealed Moaning Myrtle, her voice echoing loudly around the tiled room. “Stop! STOP!”
There was a loud bang and the bin behind Harry exploded; Harry attempted a Leg-Locker Curse that backfired off the wall be-hind Malfoy’s ear and smashed the cistern beneath Moaning Myr-tle, who screamed loudly; water poured everywhere and Harry slipped as Malfoy, his face contorted, cried, “Cruci —”
“SECTUMSEMPRA!” bellowed Harry from the floor, waving his wand wildly.
Blood spurted from Malfoy’s face and chest as though he had been slashed with an invisible sword. He staggered backward and collapsed onto the waterlogged floor with a great splash, his
wand falling from his limp right hand.
“No —” gasped Harry.
Slipping and staggering, Harry got to his feet and plunged toward Malfoy, whose face was now shining scarlet, his white hands scrabbling at his blood-soaked chest.
“No — I didn’t —”
Harry did not know what he was saying; he fell to his knees beside Malfoy, who was shaking uncontrollably in a pool of his own blood. Moaning Myrtle let out a deafening scream: “MURDER! MURDER IN THE BATHROOM! MURDER!”