Back Off Black (Sirius x Reader x Regulus)

The Black family is a complicated one, Mr and Mrs Black (Slytherins) are powerful, wealthy pure-bloods who despise the half-bloods and muggle-borns. Then there are the handsome Black sons, both are polar opposites of each other. Sirius (Gryffindor) older more rebelling son who doesn't care about blood, he found is very strange how people were willing to marry their cousins and everything with the horrible arranged marriage, uggh! Then there's Regulus (Slytherin) he follows in his parents foot steps, pranking all the mudbloods and half-bloods. he looks down on them as if they are dirt on the bottom of his shoe.