Harry drops his hand away from the redhead, turning slowly with a wide, mad grin on his face. His eyes roar at the brat with the white lines, and that fine, fine green shines with a tinge of annoyance. The fires have dimmed in them, but they glint with a vicious light, and his words eminate scorn and derision. "Stealing magic itself is far, far different from allowing it back into the endless stream of life. Magic is a river of souls, it ebbs and flows, and gives more to others and less to some. Stealing it is self-destructive; it breaks the flow of the river. If you don't know that - you are of no use to me."
His finishing line is cold and calm, filled with a loathsome venom that drips from his words like the arc of an arrow. The grin turns careless as he looks at the boy who claimed to be oh so intelligent, and continues.
"Tell you what brat. Even if you're older than you look, you can do nothing, nothing to me if you don't know what I am talking about. Would you like to? Oh, no, let me inform you"
Harry vanishes with a pop, reappearing right next to the well-dressed boy, his jacket dropping gently down onto his shoulders once more. He leans in close, his lips almost brushing the boy's ear has he whispers, his voice almost lost to the silent wind. "Fifteen inches, made of elder. Thestral tail core. Do you know it? If you do, then may god rest your damned soul, for its very essence is self-destructive, an endless death of hopelessness and depravity. I pity the ones who want it, and I damn myself with it. Remember it."
He disapparates away from the white-lined kid, reappearing near the doorway. "Oh, and you can't keep me out. Frankly, I doubt anyone could keep me out. Your walls mean nothing - nothing to me. All because of one, simplistic title, and three terrifying words. And if you ever discover it..."
He looks at the boy, and there is a haunted look this time, filled with warning and danger. "Don't say it. Never say it. Misery and despair accompany that title; and it stalks my every step," he says with a shrug, and then the mad, mad grin returns, and his eyes glitter with mirth. "You could ask someone higher up about it sometime, see their reaction to those words I told you. And then you get the absolute pleasure of knowing what you walked away from."