Harry laughs at the boy's speech, laughs long and laughs hard. "No. Stop it. You're killing me with your ignorance. Magic is in your soul yes, it is an essential part of you. But it comes from life itself. Magic is a Gift, and your every word, every filthy lie you masquerade as the truth, it goes against all that magic stands for. Your attempts to make magic fit into your limited viewpoint, your blatant hypocrisy as you ignore both my words and my titles; they aggravate me."
His wand twirls.
"You are a normal being, even with all your power, interfering in magic. Oh, and your thoughts are even more amusing - I don't 'know it all', but I do know a damn lot about soul magic, as well as the nature of magic itself. My mentor was rather good at teaching me that sort of thing. But you... you know nothing. I don't give a damn who you think you are, or if you believe me to be wrong - but I most definitely care that you continue to interfere!"
He turns away. "This is not a battle you can win. The items I hold - the power they command, that is why you cannot win. I only hope you are not a signor of the Accords, as dealing with the fallout from your death would be... tedious. Unnecessary. Unwanted, like yourself in this conversation. You know nothing of magic, you only know of death and bits and pieces of souls. If I must, I won't hesitate to invoke my rights. Being here, even your knowledge of the War, is an atrocity. You are no mage, you know no mage, you have no magic, you are nothing to the Grail. You ask why we fight for it - we fight for a wish. You ask again - and my answer is death. That is what befalls those who ignore the Grail's generous 'request'."
His eyes burn like the fires of hell themselves as he looks at the boy again, and his coat flutters in an unseen wind, and the boy is reminded of something deadly, something that he had only seen in memories and stories - Death himself, in all of his terrible glory and noble power.