and the Deathly Hallows

“That which Voldemort does not value, he takes no trouble to comprehend. Of house-elves and children’s tales, of love, loyalty and innocence, Voldemort knows and understands nothing. Nothing. That they all have power beyond his own, a power beyond the reach of any magic, is a truth he has never grasped.”

“I had proven, as a very young man, that power was my weakness and my temptation. It is a curious thing, Harry, but perhaps those who are best suited to power are those who have never sought it. Those who, like you, have leadership thrust upon them, and take up the mantle because they must, and find to their own surprise that they wear it well.”

“Do not pity the dead, Harry. Pity the living, and above all, those who live without love. By returning, you may ensure that fewer souls are maimed, fewer families are torn apart. If that seems to you a worthy goal, then we say goodbye for the present.”

Sirius Black. Albus Dumbledore.

And the Half-Blood Prince

      “I take you with me on one condition: that you obey any command I might give you at once, and without question.”
      “Of course.”
      “Be sure to understand me, Harry. I mean that you must follow even such orders as ‘run’, ‘hide’ or ‘go back’. Do I have your word?”
      “I — yes, of course.”
      “If I tell you to hide, you will do so?”
      “If I tell you to flee, you will obey?”
      “If I tell you to leave me, and save yourself, you will do as I tell you?”
      “I –“
      They looked at each other for a moment.
      “Yes, sir.”