Snape also really didn't like Harry- he just an obsession with his mother. When he died, he only wanted Harry to look at him because he has his mother's eyes.
How creepy is that? He's a grown man. Who still has a schoolboy crush. Things change- get over it. His patronus being a doe? Please. You're a greasy haired, double-agent, Death Eater who happens to work for Dumbledore, R.I.P- Lily would never fall for you. In fact, if she hadn't been killed, I bet he would still be with Moldy Voldy and his crew.
"But he was for Harry all along!" Devout Snape lovers will cry out. No, he wasn't. If he really did like Harry, he wouldn't take so many points from Gryffindor, or make fun of him and his friends. A childhood rivalry is no reason to treat their son as scum either. James and Lily Potter were brutally murdered after all.
Others are entitled to their opinions as I am to mine, but I still don't believe that Snape was on the side of good. He really wasn't ever on a side actually- always a double agent for either Dumbledore or Voldemort.