Gryffindor vs. Slytherin
Slytherins have a bad rap, especially among Gryffindors, but Gryffindors can be a bit hypocritical in their hatred against Slytherins. Here are some of the reasons Gryffindors claim to hate Slytherins:
Slytherins hate muggles and muggle-borns: First of all, Salazar Slytherin never claimed to hate muggles or muggle-borns, he just felt that the school should be kept within the wizarding community. This did not necessarily mean that he was prejudiced against muggles. Hogwarts takes special precautions to stay hidden and protected from muggles. Perhaps he thought that by allowing muggle-borns into the school, they would be running too great a risk of the muggle community finding out about the school and attracting either curious onlookers, or worse, muggles trying to destroy the wizarding world because they compare the wizards and witches to Satan worshippers. Furthermore, Salazar Slytherin never said that muggle-borns didn't belong in the wizarding community, he just didn't feel they should be taught at Hogwarts. Perhaps he had something else in mind for the education of muggle-borns. While it's true that there are some Slytherins that do harbor extreme prejudices against muggles, this does not represent the house as a whole.
For Gryffindors to make this claim about Slytherins hating muggles, aren't they guilty of stereotyping? The definition of a stereotype is judging an entire group of people based on the actions of a few.
All dark wizards have come from Slytherin: Not true! Peter Pettigrew ring any bells? He was one of the worst death eaters ever, and he came right out of Gryffindor! I would tend to bet that during the course of Hogwarts history, there have been dark wizards from each of the houses, not just Slytherin. Not only that, but there is a big difference between the phrase "All dark wizards came from Slytherin" and "All Slytherins are dark wizards". Just because most of Voldemorts followers came from Slytherin, doesn't mean that most of Slytherin are Voldemort supporters.
Slytherins think they're better than everyone else: This is one of the most hypocritical beliefs that have come out of Gryffindor house. The Gryffindors can be incredibly arrogant. From the time Harry arrived at Hogwarts, he already had it in his head that Gryffindor was the best house to be in. He knew nothing about Hogwarts or the four houses, all he knew was what he had heard from Hagrid and Ron, which was basically Slytherin=bad, Gryffindor=good.
In conclusion, I have to wonder what would have happened had Harry not had his mind tarnished with the belief that Slytherin is bad. The sorting hat considered placing him in Slytherin but he begged it not to. If he wouldn't have had all these prejudices placed in his mind regarding Slytherin, would he have been placed in that house? I wonder what the alternate universe would have looked like? Would he and Draco still hate each other, or would they be friends? Would Harry be the seeker for the Slytherin quidditch team instead of the
Gryffindor team? Would Snape still hate him?