Chapter 71: Attitudes and Conjecture
Orion didn't argue. The Killing Curse was, in truth, not especially esoteric magic; its power depended more on the caster's magical strength and intent to kill.
A hesitant heart would blunt the effect dramatically — at most producing a nosebleed.
He was merely curious — or rather, perplexed: "If I hadn't intervened, would you really have killed him?"
Regulus looked at the still-twitching cold wizard on the ground. A few seconds of silence.
On this question, he decided to tell his father the truth: "I have no qualms about killing."
"But I wouldn't use the Killing Curse for it. Not right now, at least — the Killing Curse draws too much attention."
Regulus held up his wand and examined it. "Especially with one's own wand. Too much hassle."
He went on: "Besides, there are far too many ways to kill. Without magic — physical means: snap the neck, puncture the heart, sever the artery.
With magic but no Dark Arts: Transfigure the air in his lungs into poison gas. Turn the blood in his veins to mercury. A well-placed impact spell. A fall from a great height.