I'm curious and confused about this too. If Snape really loved Lily so much, why didn't he just give up the Dark Arts/being a Death Eater so he could be with her? And if he really loved Lily, why be so horrible to Harry, even though he looked so much like James? Why was there hatred on his face when he killed Dumbledore?

I don't think he was near as bad as some Death Eaters, like Bellatrix for instance. (She's a whole other topic!) But he was a Death Eater nevertheless. I think he's a Dumbledore's man. He did make mistakes, but I think he tried to make up for them by working with Dumbledore.

My main problem with him is him treating Harry so badly. Every time Snape wanted to do something bad to Harry, he should've looked into his eyes, Lily's eyes, and resist the temptation becuase Harry is Lily's child.