Harry was alone by the lake's edge. His back was to Hogwarts, for he had no intention of turning to see the heart-wrenching damage done to the building that he had considered to be his true home. The crowd of mourners at the memorial service had dissipated long ago, leaving Harry to stare into the lake's glassy surface and think. Everyone had been affected in some way by the Battle of Hogwarts, whether by losing a friend or family member, sustaining an injury, or for at least fifty people, losing their lives. Some of the students Harry grew up with during his time at Hogwarts had lost their lives defending their school against the dark forces called up by Voldemort. Both Dumbledore's Army and the Order of the Phoenix had not been left unscathed: Several of their members had also been killed.
It was not only the Light that had had casualties. Voldemort's side also lost many Death Eaters, with many more taken into custody. Oh yes, it was victory for the Light, but that victory cost so many lives, so much spilled magical blood.
Yet there was one casualty who did not quite fit in both sides. Severus Snape had died a double agent, but had above all chosen the Light. And all because of someone Harry barely remembered-his mother. Seeing Snape's memories had been quite a shock to Harry, not really because of the "I-Must-Die-To-Save-The-Light-And-Kill-Voldemort" thing, but because of the reason why Snape had revealed the memories in the first place, had not chosen to harm Harry physically after all those Death Eater years, had chosen light over darkness.
And now that Harry had seen the truth, now that the man he once loathed was dead, somewhere beyond the reach of apology, he began to think back on how the choking vine of loathing and hatred had begun to grow. And slowly, methodically, Harry began to cut it down.
It all started, Harry mused, in first year. Oh, how he had planted and nurtured the seeds of that thick vine of hatred in only one year! Ever since he had been posed those three unanswerable questions, Harry had assumed that Snape hated him, which resulted in Harry blaming Snape for things that should have been blamed on someone else. And before the end of the year, even though Snape was innocent of attempting to steal the Sorcerer's Stone (and in fact was trying to protect it), the vine of hatred had begun to grow.
Second year came, and the incident in the Dueling Club came to mind. Didn't he think that Snape had pitted him against Draco Malfoy to humiliate Harry? Well, he reflected with a rueful half-smile, he certainly exposed something else.
Third year. Oh, third year, the year when Harry had received the Marauders' Map from Fred and George. Evidently, Snape had seen the Map for what it was almost immediately (and nearly confiscated it, if it wasn't for Lupin...) and it had responded in kind. And then Snape had sort of retaliated later in the year by painting a picture of Harry as a delusional, susceptible-to-Sirius-Black's-spells little boy. So, the vine of hatred had grown even more that year.
And then fourth year jumped on Harry. Dobby had stolen gillyweed from Snape's stores for the second task, and Snape had blamed Harry for the theft. And then...that exit from the hospital ward at Dumbledore's word at the end of the year. Before, it had never occurred to Harry about what Snape was about to do.
Fifth year brought new challenges and new fears. And the failed Occlumency, too. Did Harry hold a grudge against Snape because of those tortuous lessons? Perhaps. And with that, the vine grew more.
Sixth year. The tower. Snape casting the curse that killed Dumbledore. Oh, yes, the vine was not just a small shoot anymore. It wasn't just budding. It was a gigantic, ugly fat snake of a vine. Like a boa constrictor, it choked away any grudging acceptance Harry held for Snape (if there even was any.) And there it stood, squat, thick, shudder-inducing. There stood the nearly full-grown vine, fed on loathing, hatred, and anger.
Finally, the past year. The vine had grown to its full height when Harry had received the news that Severus Snape, the man he so hated, had become headmaster of Hogwarts. And it grew thicker when Harry and Professor McGonagall had met him in a hallway, and when Snape had dueled with the latter. And finally, there it was, the fat vine of hatred. And there it stayed until the memories were seen, the truth told, the assumptions vanquished.
And with that, the vine of hatred fell. Harry was jerked back to the lakeside, the vine uprooted and felled on the ground. It shriveled up before Harry's eyes and vanished. A feeling resounded through Harry like the solitary beat of a drum. It was peace. Harry finally found peace with the man he had once hated with every cell of his existence.
Harry stood up and headed for the castle, his mind set. He had a portrait he needed on the Headmaster's office wall. And he was going to get it on there.