Valid points about Snape. I think you are right - he was protecting Harry with the unforgivable curses. But he will never be trusted, and will likely be attacked by the Order on sight. He may turn on Voldemort at the end (along with Pettigrew, perhaps), but I still doubt he will survive book seven, or that he will have anything but a neutral reputation (like Regulus or Karkaroff) at the end.

Speaking of Regulus Black, Sirius's younger brother... A former Death Eater, later tried to get away from it and was hunted down and killed by Voldemort and crew. They say it only took one day for him to be found and killed... He really must have really pissed someone off for some reason...

JKR has never given his middle name, but his uncle's name was Alphard...