So this is basically the longest author's note ever, but I felt the need to get everything else out in a "non-story" format.
If you really get into ANY series of books, whether it be novels like Nancy Drew and the Hardy Boys, or something more 'sophisticated' from Stephen King or J.R.R. Tolkein, inevitably, by the end of it, you have reached your own conclusions about a great many things without even realizing it.
We naturally look at this as good versus evil, and the benefits of friendship and sacrifice, compassion and love; and all of those things triumphing over selfishness, arrogance, hate, and evil. But it's actually not that complicated. Rowling, like every author before her (and after her), takes an incredibly engaging conflict (good vs. evil) and takes her characters through that conflict in which the reader has become invested and leaves them standing on the other side.
But the other side of what?
Voldemort died, and now everything is hunky-dory? In this story, Wulfric Speer was ultimately unmasked and killed, and now Harry and Ginny will "go riding off into the sunset" or live "happily ever after"? We all know that that is not true. Life, in fact, can be much more difficult than everything our hero went through. Granted, I hope I never have to imagine myself doing some of the life-threatening things that Harry had to go through, but if he was honest with himself, he would probably say that the toughest thing he had to do was going through all of that without his parents.
In life, the hardest things to do, and the most difficult times we see, are the ones we have to accomplish on our own. Keeping relationships intact and thriving is a noble charge in that it is definitely more than throwing spells and memorizing plants' names. For us lowly muggles, too, no matter how well we do in school, grad school, internships, or jobs, the moments that we feel the weakest are the ones in which we feel alone.
Imagine for a moment a Navy S.E.A.L. He has to go through nothing but clandestine and dangerous missions everyday of his life, but after enough practice and enough success, he is left with the same problems as the rest of us: Love, loss, and trying to find out what the future holds.
Ah, the future…
We all do our best to protect, prepare, and perceive. Building up savings accounts and retirement funds for what's ahead, while installing security systems for what's right here, but the one thing that is forgotten most of the time is the past. What we perceived to have happened before today will affect the decisions we make in both the present and the future. And that was Harry's issue. His parents weren't in his life, and the replacements, well, an orphanage might have been better than the Dursleys. But Tom Riddle was raised in an orphanage…so what about our pasts determine our future? How far do you take the "Nature vs. Nurture" argument?
And I think THAT is what we find in these stories more than anything.
All of the characters are automatically placed into three categories: Pureblood, Half-blood, and Muggleborn. We are either black, white, or brown. We're placed with people who are the same age as us, so were they with the dormitories housing those of the same age and gender. Nature and genes definitely have a hand in our development, but then, as we saw before, why did Tom Riddle, Severus Snape, and Harry Potter all go three very different directions? So, let's look at nurture. None of the three had a good, stable role model in their lives…Riddle went completely bad, Potter went completely good, BUT Snape made the remarkable choices.
Just like Albus told Harry in his second year, "it is our choices, not our abilities, that show what we truly are." The most AMAZING thing that happened in these stories was that Severus Snape was able to change. Jodi Picoult, in one of her novels, writes that "the hardest thing in the world is believing someone can change." And I even believe that the hardest thing for anyone is to see their own faults and realize their lives are in the toilet.
As someone going through it right now, trust me, it's hard to prove to other people, and it also takes something serious to force the change in the first place. Now, onto the next more important thing…
Severus Snape didn't change WHO he was. He changed WHAT he chose to do.
He was still a jerk, haha. He still treated idiocy like it was a contagious disease. He was still a powerful person and a looming personality. None of those things changed. NONE. But when it came down to it, he made the right decisions and put himself in more danger than any other character in the entire series. People with a past like his, the unrequited love from Lily, the lack of parents, and the teasing at school from James, well, they will tend to become a "Death Eater" in the present, but they can also save Harry Potter's life in the future.
Snape was always a good man, he just didn't give off that vibe. If he was a bad man, he would not have cared that Voldemort was targeting Lily Evans that night. It would have just been another victim in a long line of victims. The fact is that moment was a huge emotional upheaval that forced him to change his WAYS, not himself.
When you fall in love with someone who has a few things wrong with their life, do you want them to change who they are? Change their personality? Change the way they think? Of course not! But if they can see situations differently, and ACT on those new realizations, then they become an even better person.
And that's what Albus was trying to tell Harry in that last scene. EVERYDAY for the rest of your life, there is going to be something that you can fix about yourself (even Bill Gates and LeBron James have that issue), but only do it because it is "what is right, not what is easy."
Harry Potter, Severus Snape, and Tom Riddle ALL had chances throughout their lives to turn away from what they knew was right, and one of them did. Two of them didn't. The wizarding world appreciates the latter.
If you continue striving for perfection, though you will never reach it (Jesus Christ is the only person that lay claim to that), you will always better the person you are. And you never know, you may save someone's life in the process…
-Jefferson Bentley Baker