Harry Potter and the Goblet of Fire
"Wonder if Percy knows all that stuff about Crouch?" Ron said as they walked up the drive to the castle. "But maybe he doesn't care ... It'd probably just make him admire Crouch even more. Yeah, Percy loves rules. He'd just say Crouch was refusing to break them for his own son."
"Percy would never throw any of his family to the Dementors," said Hermione severely.
"I don't know," said Ron. "If he thought we were standing in the way of his career ... Percy's really ambitious, you know ..." (27.207-9)
From far away, above my head, he heard a high, cold voice say, "Kill the spare."
A swishing noise and a second voice, which screeched the words into the night: "Avada Kedavra!"
A blast of green light blazed through Harry's eyelids, and he heard something heavy fall to the ground beside him; the pain in his scar reached such a pitch that he retched, and then it diminished; terrified of what he was about to see, he opened his stinging eyes." (32.16-8)
You see, I think, how foolish it was to suppose that this boy could ever have been stronger than me [...] But I want there to be no mistake in anybody's mind. Harry Potter escaped me by a lucky chance. And now I am going to prove my power by killing him, here and now, in front of you all, when there is no Dumbledore to help him, and no mother to die for him. I will give him his chance. He will be allowed to fight, and you will be left with no doubt which of us is the stronger. (33.106)