It's not that I want to try to make it seem like Snape never did anything good, this is just how the character came across to me--as somebody who did really impressive things etc., but his transformation seemed very limited to me.
ITA. That's why I keep going back to the Narcissa parallel: qualitatively, Narcissa and Snape are doing the same thing -- thwarting Voldemort because of a specific person they love -- even if Snape has *quantitatively* done more over the years. And love is a fine reason to be spurred to act; I certainly don't mean to suggest otherwise. But there's something ultimately ... selfish to me about not only Snape's love for Lily, but how he reacts in the wake of believing/learning he betrayed that love. I can't help feeling like he wouldn't have become Severus Snape, Double Agent, if Lily had survived Godric's Hollow somehow and that impression necessarily colors my view of just how heroic -- or not -- his conduct really is.
Re: part II
ITA. That's why I keep going back to the Narcissa parallel: qualitatively, Narcissa and Snape are doing the same thing -- thwarting Voldemort because of a specific person they love -- even if Snape has *quantitatively* done more over the years. And love is a fine reason to be spurred to act; I certainly don't mean to suggest otherwise. But there's something ultimately ... selfish to me about not only Snape's love for Lily, but how he reacts in the wake of believing/learning he betrayed that love. I can't help feeling like he wouldn't have become Severus Snape, Double Agent, if Lily had survived Godric's Hollow somehow and that impression necessarily colors my view of just how heroic -- or not -- his conduct really is.