Mrs Black's portrait hangs behind a pair of long, moth-eaten curtains in the entrance hall at Grimmauld Place. The portrait depicts Mrs Black as an old woman in a black cap. The occupants of the house make an effort to keep quiet, as the portrait is strongly outspoken about the presence of what she considers to be half-breeds, mutants, and freaks. When Tonks trips over the umbrella stand, causing it to crash to the ground, the curtains covering the portrait fly apart. Mrs Black is drooling, her eyes roll and the yellowing skin of her face stretches taut as she screams insults at the members of the Order, furious at their presence in her house. She is surprised and horrified when she sees Sirius, howling at her son that he is a traitor to their family. The curtains around her portrait can be closed with great effort. Once closed the old woman's screeches die down.
Walburga Black burned Sirius off the Black family tapestry after he ran away when he was sixteen. She and her husband were consumed by pure-blood mania, one of the reasons Sirius left. Although they supported Voldemort's ideals of purification of the wizarding race, getting rid of Muggle-borns and placing pure-bloods in charge, they got cold feet when they saw what the Dark Lord was prepared to do to gain power. Despite this, Sirius believes Walburga and Orion would have been proud of their son Regulus for becoming a Death Eater.