5
" Draco cast Expelliarmus. He could have, should have, attacked, but he disarmed, instead, and then attacked no further. The effort Snape has poured into this boy for the past six years has been worth it. He will not split his soul by killing. Covertly, against the efforts of Lucius, Bellatrix, and Voldemort, Snape has taught Draco non-aggression. He has fulfilled two of his three vows to Narcissa: he has watched over Draco and protected him from harm. "
― Lorrie Kim , Snape: A Definitive Reading
10
" The words to Snape’s phoenix song might have gone something like this: I am sorry I did this, so long ago. I am sorry I brought it into the world for others to use without knowing how it would hurt you. I am sorry you were so hurt by this. You didn't deserve this. I stopped doing this a long time ago, but as long as I live, I will track down all the damage I caused. If I could suffer this in your place, I would. Take my remorse. Let it re-integrate your wounds. I will sing to you until it stops. I was supposed to protect you. I will always protect you. Thank goodness it is not too late. Few moments in the series are as starkly beautiful as the tableau of Snape singing shut Draco’s Sectumsempra wounds, performing magic that nobody else in the world could cast, suffusing the song with all his grief and regret that his long-ago evil is still doing harm in the world, still hurting this child who has spent all year trying to kill people and yet doesn’t deserve this because nobody deserves this. Draco has been pushing Snape away all year, descending deeper into horror, yet when he is in danger, Snape’s protective response is absolute: I came as soon as I could. You’ll be all right. I’ve got you. I’m here. "
― Lorrie Kim , Snape: A Definitive Reading