Toujours Pur . Always pure . Those were the words emblazoned on a dark green wall, above the Black Family Tree , or , as most of the pureblood maniacs in the Black family put it , The Noble and Most Ancient House of Black . The Blacks were known for their pureblood mania , and their habit of disowning people who betrayed the family, blood traitors, basically anyone who didnt agree with their views on the wizarding world . People who associated with 'Blood Traitors . ' People who werent sorted into Slytherin . People who ran away from home . Like Sirius Black.