Please note that in this post I will be discussing the character of Severus Snape in the books, not his portrayal in the movies which I think is different in several important ways.
I'm going to be totally honest here. I think that almost everyone, whether they romanticize him or despise him, completely simplifies the character of Severus Snape. In my opinion, he's one of the most fascinating Harry Potter antagonists. And yes, he is an antagonist. You don't get to abuse your position of power over the main characters and do everything in your power to make their lives miserable and then pretend you're not an antagonist, no matter how supposedly tragic your backstory is.
A lot of people who hate Snape say that he is a completely despicable person with no redeeming qualities and that his character is not remotely interesting. I both agree and disagree. I absolutely despise Snape, and I do not forgive him for his actions, but I do not think that his character is uninteresting. I find Snape interesting in the same way I find Voldemort and Bellatrix interesting. As an antagonist.
So, from now on, I'm not going to be refuting the arguments of diehard Snape haters, because, overall, I agree with them. I am going to be refuting the arguments of those who (for some inconceivable reason), think that Snape was a good person and that all his past actions can be forgiven because of the revelation in DH.
Do you think that Snape deserves to be forgiven? He bullied his students repeatedly and showed extreme favoritism toward his own house over the others. He threatened to KILL Neville's pet toad. Like what the hell? He bullied Neville so much that he became Neville's literal worst fear. And then remember that time he got so mad that he hadn't been allowed to have Siruis' soul sucked out that he exposed Remus Lupin as a werewolf, causing him to loose his job and making the rest of his life even more difficult than it already was? How can you possibly justify that?
These are just a few examples of the horrible things that Snape did throughout the series. Pretend, just for a moment, that you had not yet read Deathly Hallows. How can you possibly excuse these actions? How can you possibly excuse a teacher psychologically abusing his students?
Now, a lot of people would answer these questions by saying, "Well, his love of Lily redeems him." This is actually one of the things about the HP series that annoys me the most. Snape's obsession with Lily is treated as "romantic" and the best thing about his characters which is just bullshit. Snape did not love Lily as a person. She was more of an object to him, a kind of symbol. This is pretty clear to me in the books. His obsession with her was understandable when he was a child, but the older he got, it became less understandable and more creepy.
Remember that time Snape found a photo of Lily and her family and then ripped that photo in half so that he could keep only the piece with Lily? Does that seem like the action of someone who loved another person unconditionally, or the action of a creepy guy who had an obsession with a woman who died at the age of 21? Snape's "love" of Lily is not romantic and it does not redeem him. It is creepy and disturbing.
I have one last point to make. If you believe that Snape was truly a good person, remember this. If Voldemort had chosen to go after Neville instead of Harry, Lily would have never been in danger and Snape would never have switched sides. If Neville had been the chosen one, Snape would still be a deatheater.
A lot of Snape haters think that it was ridiculous for Harry to forgive Snape at the end of the series. I actually disagree with this, even if I would never have forgiven Snape myself. Forgiving someone for the things they've done often has very little to do with the person being forgiven and much more to do with the person doing the forgiving. I totally understand why Harry would want to forgive Snape after he died, and how this might have helped him cope with everything.
That said, sometimes I think that J K Rowling falls into the same trap as her readers and romanticizes Snape to an extreme extent.
