Re: Oops!
Hermione read a lot but it isn't clear if she knew there was prejudice against Muggleborns in Wizarding Britain at all before arriving. She did know about the first war, but it isn't clear if she knew it was related to blood prejudice.
There is no textual evidence for proportion of half-bloods in Slytherin. 17 year old Lucius knew there are no Snapes in 'Nature's Nobility' yet he embraced young Severus.
Blood prejudice in the wizarding world takes many forms. The Weasleys avoid the squib relative. Arthur is fascinated by Muggle technology and objects to the more severe forms of Muggle baiting but doesn't even try to do business with Muggles, befriend Muggles (he only socializes with the Grangers when they come to the Wizarding World) and has no problem breaking into their home through their fireplace without their permission. Molly wants to avoid Muggles completely, 3 of the Weasley sons engage in Muggle baiting at some point. The Weasleys do invite Hermione to their home but I can't help wondering if Molly would have been as fast to believe Skeeter's story about Hermione had Hermione not been Muggle-born.
Then there is Lucius who doesn't want Muggle-borns at Hogwarts, who doesn't want his son to marry a Muggle but doesn't hold Eileen Prince's choice of husband over her son. And Bellatrix, who is horrified with the idea that Tom might be a half-blood. There is also the question of how many generations one's wizarding heritage must be to be considered a pureblood rather than a half-blood, and the fact that it matters that the Weasleys are *old* purebloods.
There is no textual evidence for proportion of half-bloods in Slytherin. 17 year old Lucius knew there are no Snapes in 'Nature's Nobility' yet he embraced young Severus.
Blood prejudice in the wizarding world takes many forms. The Weasleys avoid the squib relative. Arthur is fascinated by Muggle technology and objects to the more severe forms of Muggle baiting but doesn't even try to do business with Muggles, befriend Muggles (he only socializes with the Grangers when they come to the Wizarding World) and has no problem breaking into their home through their fireplace without their permission. Molly wants to avoid Muggles completely, 3 of the Weasley sons engage in Muggle baiting at some point. The Weasleys do invite Hermione to their home but I can't help wondering if Molly would have been as fast to believe Skeeter's story about Hermione had Hermione not been Muggle-born.
Then there is Lucius who doesn't want Muggle-borns at Hogwarts, who doesn't want his son to marry a Muggle but doesn't hold Eileen Prince's choice of husband over her son. And Bellatrix, who is horrified with the idea that Tom might be a half-blood. There is also the question of how many generations one's wizarding heritage must be to be considered a pureblood rather than a half-blood, and the fact that it matters that the Weasleys are *old* purebloods.