A/N: The challenge was to write a 100-word drabble in which one character discovers another character's secret. In this one, Harry discovers the awful truth behind one of Hogwarts' cherished traditions.
Disclaimer: Harry Potter, Godric Gryffindor, Salazar Slytherin, and all their associates are characters belonging to J.K. Rowling. I claim no rights to them, their surroundings, or their situations. Much to my sorrow.
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Three voices shouted in chorus, "Avada Kedavra!"
Three virulent green bolts struck their target. The green-clad wizard crumpled into a lifeless heap.
Briefly, all was silent.
Then the short, plump witch spoke. "N-now what?"
"We carry on as planned. The students cannot know. They wouldn't understand," a taller, sharp-eyed witch replied.
The dignified magus in red laughed, almost hysterically. "And why not? Because it was wrong? Because we just murdered--"
"It was necessary, Godric! The man was dangerous. He had to be silenced."
Sickened, Harry dropped the ancient Pensieve. It shattered, vaporous silver memories boiling away into nothing.