Snapedom

Aside: Look at what happened with Draco and the unbreakable vow. Snape has to present to his House the face of a secret DE, because some of them have parents who are DE's or DE sympathisers (those are among other Houses as well, but Snape is Head of Slytherin). So when Draco gets the order to kill Dumbledore and let DE's into the castle or else his parents are snake-dinner, he has nobody to confide in. He thinks his Head of House is a loyal DE (this plays into Dumbles' hand). Oh, he talks a good show about 'stealing glory' (which is exactly what I would've told my Head of House if I thought him to be a loyal DE. No way would I say, "I don't want to do this" or "I'm scared", because I would think it would all go back to Voldemort and then my life and my parents lives would be over) And Snape has no way to help Draco. He has to watch as this kid gets deeper and deeper in the shit, and he, the boy's Head of House, must *encourage* him on his way to ruin because Dumbledore has ordered him to 'play his part as DE teacher'. And Draco is just *one* of the dozens of children that he gets to influence over the years. A Head of House is in locis parentis nine months of the year. Children look up to their parents and parental figures, and try to emulate them. The sentiment that 'all Slytherins become DE's' to be a selffulfilling prophecy if you put an ex-DE as Head of House amd tell him to play the part of loyal DE

So, Snape is in a double bind; in order to be a good spy, he has to play the role of loyal DE to the children in his care. He has to *encourage* them when they display tendencies to Voldemort-worship.

At the same time, we see that Slytherin has become unpopular. Is this because of Voldemort? Really? We see that Lily, James and Sirius believe that 'all Slytherins are evil DE wannabees', and so does Ron Weasley, but how representative are this children? They all end up in Dumbledore's personal sphere of influence. They all become Order members. Does Dumbledore select children who are prejudiced against Slytherin or does he, gently and subtly, with the same slow poison as he poured into Harry's ears over the years, poison the minds of the most gullable, the most gung ho thrillseekers, the most simpleminded?
Ah, that is the question.

By getting rid of Slughorn, Dumbledore not only opened a way to shoehorn his pet-DE into an important slot, and used him to create the image of 'future DE' nest (or at least prologated that image and impounded it), but he also got rid of the *positive* face of Slytherin. The face of the old blood families that are open to new blood, the face of *meritocracy*.