How do you feel Harry corrected his "mistake" - of getting Sirius killed? It's not like he ever really learned Occlumency That failure to learn it ended up serving him, but that's a passive thing, not something he DID. He obviously had remorse, and I suppose he had the humility to admit, at least to himself, that he'd screwed up. But I'm not sure what could be considered his ability to make it up and change his course.

Meanwhile, I think Draco did still change his course, even though he didn't do it atop the tower, as Dumbledore had pleaded him to do. He showed remorse in his fearful and reluctant actions, he took steps to correct prior mistakes by lying about his ability to recognize Harry - which took some courage, etc. Of course, he was still a lot like Snape in that he's not exactly all hearts and flowers - but he does change from the swaggering Dark-side loving parrot we see in earlier books.

I didn't agree with everything in rexluscus' essay, but I did find it interesting and thoughtful reading - thanks for the pointer.