USING HATE.

I believe that Snape's best trick of all, better even than his performance on the night of Dumbledore's fake "murder," is his continuing trick on Voldemort.

HP-5, page 531, Snape said, "The Dark Lord... almost always knows when somebody is lying to him. Only those skilled at Occlumency are able to shut down those feelings and memories that contradict the lie, and so utter falsehoods in his presence without detection."

HP-6, page 26 (Snape to Bellatrix) "You think he is mistaken? Or that I have somehow hoodwinked him? Fooled the Dark Lord, the greatest wizard, the most accomplished Legilimens the world has ever seen?"

Well, yes, I do think so. I have suspected for a long time that Snape was faking it. The childish hostility between James and Snape when they were kids does not add up. He should have grown up and moved on by now. I am sure that Snape's carefully cultivated hatred of Harry is for a purpose.

A good actor does not just pretend; he digs deep to find something that he can really feel. Sure, Snape's grudge against Harry is real. The best lies are half-true. But Snape is hamming it way-way-way up. I also believe that Dumbledore has been tolerating Snape's bad behavior, from the beginning, because it is a part of Snape's master plan to fool Voldemort.

Snape is able to "shut down those feelings and memories that contradict the lie," but that is not enough. Eventually, Voldemort would notice a blank, stone wall where a person with emotions should be. Snape needs to fill that blank space with something credible. Voldemort does not have the social / emotional depth to psychoanalyze Snape. Being a certified psychopath himself, he has no trouble believing the hate in Snape to be blinding. While intelligent enough in some ways, Voldemort is not big on people skills. He will see this strong emotion and believe it. And Snape can use it as a cover for whatever he is really up to.

Dumbledore, too, is fooling Harry so that Voldemort will believe these frauds -- both the "murder" and Snape's hate. Dumbledore is taking advantage of the fact that Harry never mastered Occlumency. It is all for a good cause, and I am sure that Harry will approve and forgive in the end.

Snape's lie to Bella, that he believed Voldemort dead, underlined this theme. Of course he knew. Even Hagrid knew that Voldemort would return. Snape and Dumbledore had been anticipating Voldemort's return from the day he vanished. Snape has been posing all along.