I have always been bothered by the seemingly concrete idea that anyone from the Slytherin house is automatically bad/evil/a villain. I really think this is only what we`re supposed to believe at this point. Now that I think about it, isn`t it kind of weird how there`s only a small handful of Slytherin students that we know that much about? The only students we know for sure come from families that support Voldemort are Malfoy, Crabbe, and Goyle, and the only other person that is even mentioned that often is Parkinson. (Rule #2)
Most of the Slytherins that we know enough to hate are Purebloods from the biggest Pureblood families - the Blacks, the Malfoys, the Lestranges, etc. But I was very interested by this hint in the chapter 6 section of New Clues: "HP sleuths should have been taking very careful notes as Sirius described the background on each member of his family. One thought that should be flitting through the heads of HP sleuths is that it`s not always which Dark Wizards are on that Pureblood tapestry, but which ones are not." I think they`re trying to hint at Snape here. I believe that Snape probably isn`t a Pureblood. We know that it`s possible for someone who isn`t pure to be sorted into Slytherin house because Tom Riddle was. Even though Riddle ended up being just a little bit on the evil side and Snape isn`t very nice even if he really doesn`t support Voldie anymore, couldn`t there possibly be a whole other "breed" of Slytherins out there that we haven`t become acquainted with? They could be people who either don`t support Voldemort`s ideas or can`t really fit in with those who do anyway because they aren`t Pureblood, but got into Slytherin house because they actually possess the personality traits that the Sorting Hat suggests in his songs.
In the last book JKR has really been putting a lot of emphasis on the idea that all the houses are going to have to stick together in order to resist Voldemort, so it sounds like there could be some level of friendship established between some Slytherins and the other houses in the next books. What do you think?