I know Snape thinks voldomort is evil and he wants him gone but i think snape just hates the fact that harry is in gryffindor and he keeps getting into all this trouble while hes risking his neck to keep harry alive. Snape is a closet case sweetheart and I think hes going to have a lot to do with voldomorts downfall. I mean it's not like voldomort would ever take snape back now and snape knows it.