I came across this post in Tor.com. http://www.tor.com/blogs/2013/04/severus-snape-does-not-deserve-your-pity. Although it's an older article, it was one of the most well-written and accurate analysis of one of my favorite Harry Potter characters, Severus Snape.
JK Rowling is brilliant and did a great job of creating a disturbed, flawed character, that many people, including myself can empathize with. But, don't misunderstand him or pity him!
