Edmund has always been one of my favorite fictional characters. I suppose it’s because he’s the one we relate to—he’s the one who screwed up, big time, and caused everyone else suffering and distress because of his selfishness. Aslan died for him.
And Edmund had the grace to accept that, and to become a better and bigger person than he was before. But I think that every time he saw Aslan after that, he would look at Aslan’s face again, and be reassured yet again—I think that Aslan always took a moment to whisper to him—“You were worth it.” And I think that the reason that Edmund went on to become a gracious king—King Edmund the Just—and a better person, was not necessarily the feeling that he owed Aslan anything—to say that was to take away the beauty of Aslan’s sacrifice—but because he loved Aslan, and yearned to become a man who was worthy of the sacrifice that had been made for him.