Severus Snape is a very complex character from the very beginning. Obviously, he plays the role of the villain for a lot of the first four books with little mention of exactly why. It is clear that he hated Harry Potter for being James Potter's son. It isn't until Harry Potter and the Order of the Phoenix that we finally get a picture of the man that isn't the 'evil potions master'. we learn that Severus has a very large dislike, verging on hatred, towards Harry. The plot thickens when Albus tells Harry that Severus owed James Potter a life debt and he was repaying it by keeping Harry out of danger. That is the first of many conflicting ideas with Severus Snape. Everyone who read Harry Potter and the Deathly Hallows or even just saw the movies will understand why that is significant for Severus Snape.
Snape is a complicated man. He's bitter. He's … spiteful. He's a bully. All these things are still true of Snape, even at the end of this book. But was he brave? Yes, immensely. Was he capable of love? Very definitely. So he's – he's a very – he was a flawed human being, like all of us.
Harry forgives him – as we know, from the epilogue, Harry – Harry really sees the good in Snape ultimately. I wanted there to be redemption and I wanted there to be forgiveness. And Harry forgives, even knowing that until the end Snape loathed him unjustifiably. it's totally, totally unfair that he loathes him so much
I'm not going to say that Severus Snape is my favourite character, far from it, but I can respect the character.