Broken
After the war someone had to put Harry back together again, after all, and who better to do it? It was important that Harry be fixed because a lot of people had looked up to him for a very long time. But by then there was not very much left of Harry and what there was were mostly shards like an egg that has been put in a garbage disposal. It took a special sort of fellow to put pieces that small together and come out with a pretty, glittering mosaic that was better than the original. All the king's horses and all the kings' men could not have done it and Dumbledore did not even try as it happens.
Certain pieces were missing, or too fragile to glue in place, but enough thick white paste around the edges can cover a multitude of small evils and it is not as if anyone expected perfection here. They are simply glad to get their glassy-eyed cardboard hero back and make no protests as to his condition: one slightly battered savior, bit wonky 'round edges, faint smell of cat, from non-smoking home. As a matter of fact they would probably have done perfectly well with a cardboard Harry Potter cutout gripping a cardboard wand and with a cardboard owl on his shoulder. What was left was dealing with the real Harry, who is a few chessmen short of a set. It took a certain amount of courage, doing that.
Not just anyone wants to pick up barbed wire barehanded, any more than just anyone wants to be locked in a room with a madman. Maybe you have to be a little mad yourself, to face, with equanimity, Harry Potter with drool down his front and wild eyes and bleeding fingers from clawing at the door. Perhaps only a madman or a visionary would guess or see that here were enough pieces left to make the jigsaw puzzle worth struggling with.
It took a long time, not just rebuilding Harry but making him sane. Only a master, and only someone who loved him very much, who was tied to him by destiny--only this one person could even hope to succeed. Even then it was not a pleasant task. Harry had any number of hang-ups, small things he needed to get over, things that added together made him intractable but subtracted would return him to useful.
The things that Harry had trouble getting over were all overcome one by one, from his grief at losing his godfather to his rage at the injustice of the way things had turned out. Harry had to be taught that things he had believed unquestioned were questionable--often morally questionable, at that. There is nothing more difficult than teaching an old dog new tricks but in the end nothing succeeds like success. Harry, once converted, was a model for the new world order, a brilliant example of the principle that a man is made and not born. He was everything Voldemort had dreamed of and more.