While I don't know much about Alan Rickman I know alot about Snape. He was a bully, a hero, a bigot, and a savior. No one could have played him better. Alan brought to life the professor who gave us chills as we read the books that J.K. Rowling created.
Snape was a complicated character to say the least. He was the teacher we all hated. That teacher that played favorites and picked on the weak. While we felt bad for him after reading/seeing his back story, many of us just cant forgive his acts against Harry and others.
He was a good man but only after causing so much pain. We don't know much about Severus' time as a Death Eater, but we do know that if Snape hadnt spied for Voldemort then he would never have known about the prophecy. Snape tried to bargain for Lily's life but didn't care at all about the innocent Harry. If he had never started running with people like Malfoy and messing with the Dark Arts then he would have stayed Lily's friend.
Snape sacrificed so much to be part of the group. His friendship, love, and true happiness were taken from him. I pity Snape. He was a great man for protecting Harry. His heart was doing it to make it up to Lily. If he had not sacrificed not just his life but his pride to protect James' son we would not have had a happy ending.
So we thank you Alan Rickman for doing justice to such a brilliant character.