Snape vs. Snape

Bad Snape

• Severus Snape kills Dumbledore using the "Avada Kedavra, " a you-gotta-mean-it-for-it-to-work Unforgivable Curse.
• Once a Voldemort-lovin', half-blood-hatin' Death Eater, always a Voldemort-lovin', half-blood-hatin' Death Eater.
• He's a master of Occlumency, the "magical defense of the mind against external penetration." Few can see through his lies.
• Despite "trusting" Snape, Dumbledore refrains from appointing his former pupil Professor of Defense Against the Dark Arts for years. The second he gets the job? Death all around.
• Dumbledore admits that being "rather cleverer than most men," his mistakes are "correspondingly huger." Trusting a man who betrayed him before? Huge mistake.
• Harry's been saying it all along.

Good Snape

• Snape must fulfill his do-or-die Unbreakable Vow to protect Dumbledore's would-be assasin, Draco Malfoy--preserving his cover as a double agent. So he reluctantly kills the Hogwarts headmaster only to continue spying for the Order of the Phoenix.
• Dumbledore was ordering Snape to kill him, not begging for his life. He'd never beg!
• Even while battling Harry, Snape reminds him to "keep your mouth shut and your mind closed"--sound advice for his former Occlumency pupil. Plus, Snape has rescued Harry several times--however begrudgingly--and even tells the Death Eaters in book 6 to hold off on killing him, supposedly under Voldemort's "orders."
• Dumbledore trusts him "completely." That's good enough for us.

-courtesy of Entertainment Weekly