So after Snape is killed by Voldemort, it is revealed that he's actually been a good guy and has been protecting Harry more than anybody the entire time, and the reason he killed Dumbledore was to save Draco from having to do so and to gain Voldemort's ultimate trust.
The problem I have with it is, what exactly was gained by Snape killing Dumbledore? Sure, Voldemort know trusted him, which allowed Snape to infiltrate the Death Eaters and Voldemort's inner circle, but what exactly did he accomplish from that position? He was pretty much seen as a random Death Eater. Maybe he leaking info back to The Order? But with Dumbledore and Sirius dead The Order was pretty much useless. Wouldn't he be much better served as a full-fledged member of Team Good, helping Harry find and destroy the Horcruxes, teaching him Occlumency, and eventually being another wand at The Battle of Hogwarts?
All he really accomplished I suppose was keeping the students of Hogwarts somewhat safe as if he weren't Headmaster than Amycus Carrow probably would be. But since he had to keep up the facade in front of the other Death Eaters at the school, he even failed at this really. The Carrows were torturing students and eventually there was a massive battle at the school and a bunch of students were put in incredible danger (and a good number of them died).
So yeah.
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