“Potter, precious Potter, obviously he wanted a look at the Chosen One,” sneered Malfoy, “but that Weasley girl! What’s so special about her?”

“A lot of boys like her,” said Pansy, watching Malfoy out of the corner of her eyes for his reaction. “Even you think she’s good-looking, don’t you, Blaise, and we all know how hard you are to please!”

“I wouldn’t touch a filthy little blood traitor like her whatever she looked like,” said Zabini coldly, and Pansy looked pleased. Malfoy sank back across her lap and allowed her to resume the stroking of his hair.

Ron: "My whole family are blood traitors! That's as bad as Muggle-borns to Death Eaters!"

“The pure-blood families are all interrelated,” said Sirius. “If you’re only going to let your sons and daughters marry pure-bloods your choice is very limited; there are hardly any of us left. Molly and I are cousins by marriage and Arthur’s something like my second cousin once removed. But there’s no point looking for them on here—if ever a family was a bunch of blood traitors it’s the Weasleys.”

Trisha Mittal for the Hindustan Times India - My question is why is the Weasleys' clock set at Mortal Peril?

JK Rowling: Mrs Weasley is right, if you don't know what I'm talking about, the Weasleys have a clock in which each of the 9 hands represents a member of the family and they point at things like at work, travelling and so on. Well at the beginning of this book all 9 hands are pointing at mortal peril. Mrs Weasley is right, she hopes that everyone is now in danger and she is correct. Well if the Death Eaters had clocks their hands wouldn't point at mortal peril. And the Weasley are what are called blood traitors; in other words they are pure-blood but don't act that way. They consort and like muggles. Therefore they are in the firing line, they would not be among Voldemort's favourite people?

A minority of these families publicly deplored their inclusion on the list, declaring that their ancestors certainly included Muggles, a fact of which they were not ashamed. Most vocally indignant was the numerous Weasley family, which, in spite of its connections with almost every old wizarding family in Britain, was proud of its ancestral ties to many interesting Muggles. Their protests earned these families the opprobrium of advocates of the pure-blood doctrine, and the epithet 'blood traitor'. Meanwhile, a larger number of families were protesting that they were not on the pure-blood list.